Genetics and Rare Diseases Research

Finding the root cause of bronchiolitis symptoms

January 24, 2018

A new study shows that steroids might work for rhinovirus but not for respiratory syncytial virus.

Every winter, doctors’ offices and hospital emergency rooms fill with children who have bronchiolitis, an inflammation of the small airways in the lung. It’s responsible for about 130,000 admissions each year. Sometimes these young patients have symptoms reminiscent of a bad cold with a fever, cough and runny nose. Other times, bronchiolitis causes breathing troubles so severe that these children end up in the intensive care unit.

“The reality is that we don’t have anything to treat these patients aside from supportive care, such as intravenous fluids or respiratory support,” says Robert J. Freishtat, M.D., M.P.H., chief of emergency medicine at Children’s National Health System. “That’s really unacceptable because some kids get very, very sick.”

Several years ago, Dr. Freishtat says a clinical trial tested using steroids as a potential treatment for bronchiolitis. The thinking was that these drugs might reduce the inflammation that’s a hallmark of this condition. However, he says, the results weren’t a slam-dunk for steroids: The drugs didn’t seem to improve outcomes any better than a placebo.

But the trial had a critical flaw, he explains. Rather than having one homogenous cause, bronchiolitis is an umbrella term for a set of symptoms that can be caused by a number of different viruses. The most common ones are respiratory syncytial virus (RSV) and rhinovirus, the latter itself being an assortment of more than 100 different but related viruses. By treating bronchiolitis as a single disease, Dr. Freishtat says researchers might be ignoring the subtleties of each virus that influence whether a particular medication is useful.

“By treating all bronchiolitis patients with a single agent, we could be comparing apples with oranges,” he says. “The treatment may be completely different depending on the underlying cause.”

To test this idea, Dr. Freishtat and colleagues examined nasal secretions from 32 infants who had been hospitalized with bronchiolitis from 2011 to 2014 at 17 medical centers across the country that participate in a consortium called the 35^th Multicenter Airway Research Collaboration. In half of these patients, lab tests confirmed that their bronchiolitis was caused by RSV; in the other half, the cause was rhinovirus.

From these nasal secretions, the researchers extracted nucleic acids called microRNAs. These molecules regulate the effects of different genes through a variety of different mechanisms, usually resulting in the effects of target genes being silenced. A single microRNA typically targets multiple genes by affecting messenger RNA, a molecule that’s key for producing proteins.

Comparing results between patients with RSV or rhinovirus, the researchers found 386 microRNAs that differed in concentration. Using bioinformatic software, they traced these microRNAs to thousands of messenger RNAs, looking for any interesting clues to important mechanisms of illness that might vary between the two viruses.

Their findings eventually turned up important differences between the two viruses in the NF-kB (nuclear factor kappa-light-chain-enhancer of activated B cells) pathway, a protein cascade that’s intimately involved in the inflammatory response and is a target for many types of steroids. Rhinovirus appears to upregulate the expression of many members of this protein family, driving cells to make more of them, and downregulate inhibitors of this cascade. On the other hand, RSV didn’t seem to have much of an effect on this critical pathway.

To see if these effects translated into cells making more inflammatory molecules in this pathway, the researchers searched for various members of this protein cascade in the nasal secretions. They found an increase in two, known as RelA and NFkB2.

Based on these findings, published online Jan. 17, 2018, in Pediatric Research, steroids might work for rhinovirus but not for RSV, notes Dr. Freishtat the study’s senior author.

“We’re pretty close to saying that you’d need to conduct a clinical trial with respect to the virus, rather than the symptoms, to measure any effect from a given drug,” he says.

Future clinical trials might test the arsenal of currently available medicines to see if any has an effect on bronchiolitis caused by either of these two viruses. Further research into the mechanisms of each type of illness also might turn up new targets that researchers could develop new medicines to hit.

“Instead of determining the disease based on symptoms,” he says, “we can eventually treat the root cause.”

Study co-authors include Kohei Hasegawa, study lead author, and Carlos A. Camargo Jr., Massachusetts General Hospital; Marcos Pérez-Losada, The George Washington University School of Medicine and Health Sciences; Claire E. Hoptay, Samuel Epstein and Stephen J. Teach, M.D., M.P.H., Children’s National; Jonathan M. Mansbach, Boston Children’s Hospital; and Pedro A. Piedra, Baylor College of Medicine.

Newborn screening leader selected to advisory committee on heritable disorders in newborns and children

January 11, 2018

Sarah Viall, PPCNP, coordinator for the Newborn Screening Program at the Children’s National Rare Disease Institute (CNRDI), has been invited to serve on the Education and Training Workgroup of the Health Resources & Services Administration’s (HRSA) Advisory Committee on Heritable Disorders in Newborns and Children (ACHDNC).

Established under the Public Health Service Act, the ACHDNC focuses on reducing morbidity and mortality in newborns and children who have, or are at risk for, genetic disorders. The Committee currently recommends that all newborn screening programs include a Uniform Screening Panel that monitors for a total of 34 core disorders and another 26 secondary disorders.

In addition to developing recommendations on national newborn screening guidelines, the ACHDNC also advises the U.S. Department of Health and Human Services Secretary on the most appropriate application of newborn screening technologies, tests, policies and standards. The Committee provides technical information that helps develop Heritable Disorders Program policies and priorities that enhance the ability of local and state health agencies to provide screening, healthcare services and counseling for newborns and children affected by genetic disease.

Viall had previously spent a year observing meetings for the ACHDNC Education and Training Workgroup.

“I am thrilled to be an official member that can contribute to the important work of educating communities about newborn screening,” says Viall.

$3M Retrophin gift establishes Rare Disease Network at Children’s National

January 10, 2018

“This is an exciting first step toward a new era of rare disease care and innovation,” says Marshall Summar, M.D., director of the CNRDI. “We are grateful for this gift from Retrophin that will help us accelerate progress for our patients and families and pursue work that will have a far-reaching impact on both children and adults across the country and around the world thanks to the support of Retrophin.”

Children’s National Health System and Retrophin, Inc. have announced the creation of the Retrophin Rare Disease Network at Children’s National. Retrophin, a biopharmaceutical company specializing in identifying, developing and delivering life-changing therapies to people living with rare diseases, has committed $3 million over the next six years to support the work of the Children’s National Rare Disease Institute (CNRDI). Retrophin’s commitment marks the first corporate gift to CNRDI.

“One of the chief challenges of 21st century pediatric medicine is our continued inability to provide more help to those born with rare genetic diseases,” says Marshall Summar, M.D., director of the CNRDI. “This is an exciting first step toward a new era of rare disease care and innovation. We are grateful for this gift from Retrophin that will help us accelerate progress for our patients and families and pursue work that will have a far-reaching impact on both children and adults across the country and around the world thanks to the support of Retrophin.”

As a dedicated source of funding, the Retrophin Rare Disease Network will advance the CNRDI’s efforts to create a global “hub and spoke” model for disseminating and streamlining patient access to optimal care methods and among national and international peer institutions. The network will enhance the field of rare disease medicine by standardizing care models and establishing world-wide best practices in diagnosis and treatment.

The Retrophin Rare Disease Network will also provide funding for new dedicated positions at the CNRDI and build on the Institute’s existing digital and telemedicine programs, to extend the reach of its researchers and caregivers in areas where there is currently limited care available for children and adults living with rare diseases.

CNRDI is a first-of-its-kind center focused exclusively on advancing the care and treatment of children and adults with rare genetic diseases. The first National Organization for Rare Disorders (NORD) Center of Excellence, it aims to provide a medical home for patients and families seeking the most advanced care and expertise for rare genetic conditions that remain largely unknown to the general medical community.

New clues to detect rare pediatric cancers

January 4, 2018

Using germline and tumor testing and centralized pathology review, a research team that included D. Ashley Hill, M.D, and Joyce Turner found that Sertoli-Leydig cell tumor and gynandroblastoma are nearly always DICER1-related tumors.

Children’s National Health System researchers played a key role in a new study exploring the clinical and genetic qualities of a group of rare, potentially deadly cancers that affect infants, children and adolescents. The research team’s findings suggest that genetic testing for people at risk may aid in earlier, more accurate diagnoses of these cancers, leading to early-stage treatment that could greatly improve survival.

Ovarian sex cord-stromal tumors (OSCST) include juvenile granulosa cell tumors (JGCT), Sertoli-Leydig cell tumor (SLCT) and gynandroblastoma (GAB). Mutations in the DICER1 gene often have been noted in children with these cancers, as well as in those with a particularly lethal pediatric lung cancer called pleuropulmonary blastoma (PPB). All of these cancers are highly curable if caught early but, at later stages, can be aggressive and often fatal.

Using germline and tumor testing and centralized pathology review, the research team found that SLCT and GAB are nearly always DICER1-related tumors. There also may be a much stronger association between SLCT and DICER1 than was previously appreciated. The new findings have implications for earlier detection and diagnoses of these cancers, as well as for screening other family members. The study was published in the December 2017 edition of Gynecologic Oncology.

“These types of tumors are diverse, relatively rare and understudied,” says D. Ashley Hill, M.D., the study’s senior author and a professor in the Division of Pathology and Laboratory Medicine at Children’s National. “Sertoli-Leydig cell tumor, for instance, is a unique genetic and pathologic entity and this rare cancer of the ovaries can be hard to detect. Using the testing process from this study, we now may be able to classify these tumors more accurately.”

The study authors assessed the first 107 individuals enrolled in the International Ovarian and Testicular Stromal Tumor Registry. They obtained medical and family history, and they conducted central pathology review plus DICER1 gene sequencing on blood and tumor tissue. Thirty-six of 37 patients with SLCTs and all four patients with GABs they tested showed DICER1 mutations, and half of those with SLCT had germline or mosaic mutations. The team noted that individuals with predisposing DICER1 mutations had significantly better overall and recurrence-free survival.

Based on their findings, the study authors recommend:

Careful and ideally centralized pathologic review for all individuals with OSCST tumors
DICER1 testing for all those with SLCT and GAB and
Consideration of DICER1 testing for patients with other OSCSTs.

“Genetic testing may be useful for screening and diagnosing entire families if one family member tests positive for a DICER1 mutation, especially to determine if they are at risk for PPB. When we know who is at risk, we can protect all children in a family,” Dr. Hill says. “Ultimately we may be able to cure this deadly lung cancer, PPB, by identifying and performing computed tomography scans on people who are at risk, so we can catch these cancers early.”

Dr. Hill thinks future research may study children whose cancer was not detected early or has become resistant to chemotherapy. They also may explore ways to restore normal controls in cancer cells, so they follow normal paths of development, for the purpose of developing targeted treatments with fewer side effects than current therapies.

In addition to Dr. Hill, other Children’s National study co-authors include Amanda Field, M.P.H., Department of Pathology; Weiying Yu, Ph.D., Department of Pathology; and Joyce Turner, director of the Cancer Genetic Counseling Program in Children’s Rare Disease Institute.

Other members of the study team are experts from the International Ovarian and Testicular Stromal Tumor Registry, Children’s Minnesota, Washington University Medical Center, Carolinas Health Care System, University of Texas MD Anderson Cancer Center, Harvard Medical School, University of Colorado School of Medicine, Clinic of Pediatrics (Dortmund, Germany), National Cancer Institute and Dana-Farber Cancer Institute.

Research reported in this story was supported by the National Institutes of Health under award number NCI R01CA143167, The Parson’s Foundation, St. Baldrick’s Foundation, Pine Tree Apple Tennis Classic Foundation, Hyundai Hope on Wheels, the Randy Shaver Cancer Research and Community Fund, the German Childhood Cancer Foundation and the Intramural Research Program of the Divisions of Cancer Epidemiology and Genetics, National Cancer Institute.

Internationally renowned pediatric nephrologist named to NIH advisory council

January 4, 2018

Pediatric nephrologist Lisa M. Guay-Woodford, M.D., has been named to a three-year term as adviser serving on the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) Kidney, Urologic and Hematologic Diseases subcouncil.

Dr. Guay-Woodford, Director of the Center for Translational Science at Children’s National, is an internationally recognized expert in the mechanisms that modulate the clinical severity of certain inherited renal disorders, such as autosomal recessive polycystic kidney disease. She holds the Richard L. and Agnes F. Hudson Professorship in Health Services Research at Children’s National.

NIDDK, like other grant-awarding institutes within the National Institutes of Health (NIH), looks to its advisory councils for feedback on procedures that govern staff and manage its grant portfolios. The institute, the fifth largest at the NIH, supports clinical research about internal medicine and related subspecialties for many of the most common chronic health conditions.

“It is a tremendous honor to be asked to serve on this important council. I look forward to providing advice and perspective on the exciting portfolio of NIDDK-funded projects,” Dr. Guay-Woodford says.

Researchers discover new gene variant for inherited amino acid-elevating disease

December 29, 2017

Carlos Ferreira Lopez

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What’s known

Hypermethioninemia is a rare condition that causes elevated levels of methionine, an essential amino acid in humans. This condition stems from genetic variations inherited from one or both parents. Some forms of hypermethioninemia are recessive, meaning that two copies of defective genes are necessary to cause this disease. Other forms are dominant, meaning that only one copy can cause hypermethioninemia. Recessive forms of the disease tend to have more serious consequences, causing elevated methionine levels throughout life and leading to changes in the brain’s white matter visible on magnetic resonance imaging that can cause neurological problems. The dominant forms are generally thought to be largely benign and require minimal follow-up.

What’s new

A research team led by Carlos Ferreira Lopez, M.D., a medical geneticist at Children’s National Health System, discovered a new gene variant that had not been associated with hypermethioinemia previously when an infant who had tested positive for elevated methionine on newborn blood-spot screening came in for a follow-up evaluation. While the majority of dominant hypermethioninemia are caused by a genetic mutation known as MAT1A p.Arg264His, the child didn’t have this or any of the common recessive hypermethioninemia mutations. Genetic testing showed that she carried a different mutation to the MAT1A gene known as p.Ala259Val, of which she carried only a single copy. The child fit the typical profile of having the dominant form of the disease, with methionine levels gradually declining over time. Testing of her mother showed that she carried the same gene variant, with few consequences other than a hepatitis-like illness as a child. Because liver disease can accompany dominant hypermethioninemia, the infant’s doctors will continue periodic follow-up to ensure she remains healthy.

Questions for future research

Q: Besides the potential for harmful liver effects, does dominant hypermethioninemia have other negative consequences?

Q: How common is this gene variant, and are certain people at more risk for carrying it?

Source: “Confirmation that MAT1A p.Ala259Val mutation causes autosomal dominant hypermethioninemia.” Muriello, M.J., S. Viall, T. Bottiglieri, K. Cusmano-Ozog and C. R. Ferreira. Published by Molecular Genetics and Metabolism Reports December 2017.

U.S. leads the pack in medical genetics and genomic medicine

December 28, 2017

Debra S. Regier, M.D., Ph.D., a pediatric geneticist who is the director of education in the Rare Disease Institute at Children’s National Health System.

It long has been recognized that traits can be passed down from parents to offspring in humans, just as occurs with other species. But medical genetics – the scientific field that covers the diagnoses and management of heritable diseases – didn’t get its start until recently. Only in the past century or so have researchers devoted significant resources to better understanding the patterns of inheritance or syndromes that have a genetic cause.

Although this research has taken place around the world, the United States is well established as a leader in this field, say authors of an article published in the July 2017 issue of Molecular Genetics & Genomic Medicine.

This article covers the history of the field, demographics of genetic conditions, legislation that relates to genetic disease and its burdens and highlights a long list of American researchers who have genetic diseases named after them. The list, comprising 86 scientists in a diverse array of fields including pediatrics, pathology, dermatology and oncology, is a testament to the devotion of these researchers to understanding a specific condition or, sometimes, group of related conditions.

Their dedication, often spanning the entirety of their career, contributed to the wealth of knowledge now available that’s improved the outcomes of many individuals with these diseases, says article co-author Debra S. Regier, M.D., Ph.D., a pediatric geneticist who is the director of education in the Rare Disease Institute at Children’s National Health System.

“Because these researchers spent their lives characterizing these disorders,” Dr. Regier says, “we can use that information when we find a child who fits the scheme of a particular disorder to tell families what they can expect – and in many instances – explain how best to treat them.”

Beyond tracking heritable disease traits through families, modern genomics also has led to the ability to recognize specific genes that cause various disorders, speeding the process of diagnosis and intervention.

“There are about 7,000 rare diseases, and sometimes it’s hard to know where to start with patients because it’s unclear which one they have,” Dr. Regier says. “By doing genetic testing, we can give families information, offer a prognosis and start treatments that have helped children who came before them with the same genetic mutation.”

Dr. Regier speculates that U.S. leadership in this field is largely due to the presence of large academic centers that are devoted to the study of genetic disorders, like Children’s National. Such centers give researchers dedicated time and space to better understand genetic diseases, both on a basic and an applied level. Despite the country’s stature as a frontrunner in this research arena, the United States has a relatively small medical genetics community, which researchers can use to their advantage.

“If I find a child with a rare genetic disorder, I can call up the world expert on this condition to share and receive information,” Dr. Regier adds. “That’s relatively rare in science, but it happens all the time in our field because we’re so small.”

Although the United States has contributed to many medical genetics and genomic medicine advances that have helped patients worldwide, the history of the field in this country wasn’t always laudable, Dr. Regier says. The article also addresses the eugenics movement during the early 20^th century. For example, in 1907, Indiana became the first state to enact involuntary sterilization legislation, an effort to remove “flawed” individuals from the gene pool that was followed by similar laws in several other states. In 1924, Virginia enacted a law that allowed eugenic sterilization of people with intellectual disabilities that was upheld by the U.S. Supreme Court in 1927.

After atrocities committed by the Nazis during World War II, when the repercussions of these policies became more clear, these laws were gradually abolished.

More recent legislation, the article’s authors write, aims to protect individuals from discrimination for genetic disorders. Thus far, 35 states have laws on the books protecting against employment discrimination, and 48 states passed legislation against health insurance discrimination based on genetic information. Twenty-four states endorsed statutes that limit the use of genetic information for other types of insurance, including life, long-term care and disability.

The article is the first of a two-part series and was followed Nov. 26, 2017 by a second article addressing the current status of prenatal testing, reproductive options and reproductive law in the United States, as well as newborn screening, genetic services, rare disease registries, and education and training in genetics.

“We can take pride in our progress, while still acknowledging that we have a long way to go in this field,” Dr. Regier says.

Children’s National leaders join with Governor Martin O'Malley

Facial analysis technology successfully used to identify Noonan syndrome in diverse populations

December 6, 2017

According to an international study led by the National Human Genome Research Institute (NHGRI), researchers have successfully used facial analysis software, developed by the Sheikh Zayed Institute for Pediatric Surgical Innovation at Children’s National, to identify Noonan syndrome in diverse populations.

Noonan syndrome is relatively common, affecting between 1 in 1,000 to 1 in 2,500 children, however few studies have been conducted in non-Europeans. For this study, the researchers evaluated children (average age of eight) with Noonan syndrome from 20 countries. Using the facial analysis software and clinical criteria, the researchers compared 161 white, African, Asian and Latin American children with Noonan syndrome with 161 people of the same age and gender without the disease. Using the software to analyze facial features, they were able to correctly diagnose patients with the disease from each ethnic group with 94 percent or higher accuracy.

“Our algorithm found widely spaced eyes as a significant facial feature in all ethnic groups and also highlighted facial features that are relevant to diagnosing the syndrome in each group,” said

Marius George Linguraru, D.Phil., developer of the facial analysis technology and an investigator in the study from Children’s National.

Linguraru and his team are working to create a simple tool that will enable doctors in clinics without state-of-the-art genetic facilities to take photos of their patients on a smartphone and receive instant results.

Research led by Zhe Han featured on cover of JASN, leading kidney disease journal

December 5, 2017

Coenzyme Q10, one of the best-selling nutrient supplements to support heart health also could be beneficial for kidney health, according to research conducted in transgenic fruit flies that was led by Zhe Han, Ph.D., associate professor at Children’s Center for Cancer and Immunology Research.

Nephrocytes, filtration kidney cells in Drosophila, require the Coq2 gene for protein reabsorption, toxin sequestration and critical cell ultrastructure. Silencing the Coq2 gene results in aberrantly localized nephrocyte slit diaphragms and deformed lacunar channels, Han and co-authors found. Nephrocytes closely resemble the podocytes of the human kidney.

The research team’s paper, published online April 2017, this fall was featured on the cover of Journal of the American Society of Nephrology, the No. 1 kidney disease journal.

“I am honored that the JASN editors chose to feature my lab’s work on the cover of this prestigious journal,” Han says. “This underscores the utility of our gene-replacement approach, which silenced the fly homolog in the tissue of interest – here, the kidney cells – and provided a human gene to supply the silenced function.”

Long-term glucocorticoids help patients with DMD

December 4, 2017

Glucocorticoids, a class of steroid hormone medications, have definite long-term benefits for patients with Duchenne muscular dystrophy, including extending muscle strength and function over years and decreasing the risk of death.

There is currently no cure for the devastating, progressive neuromuscular disease known as Duchenne muscular dystrophy (DMD). But clinics that treat patients with this disease have long relied on a class of steroid hormone medications, known as glucocorticoids, to ease its symptoms. Over weeks and months, these drugs help preserve muscle strength and function. Though these short-term benefits have been clear, some physicians have balked at using these medications over the long term – their benefits over years was unknown, making their potential side effects not worth the risk.

Now, a study published online Nov. 22, 2017 in The Lancet suggests that these medicines have definite long-term benefits, including extending muscle strength and function over years and even decreasing the risk of death. These findings support what has become the standard prescribing practice at many clinics and could help sway parents who are on the fence about their children receiving these therapies.

DMD is characterized by loss of muscle function and progressive muscle weakness that begins in the lower limbs and typically affects males due to the location of its causative genetic mutation. Patients with this devastating neuromuscular disease often receive glucocorticoids at some point as the disease progresses. Studies since the late 1980s have confirmed short-term benefits of treating with these drugs, including delaying the loss of muscle strength and function.

However, no prospective study had followed long-term glucocorticoid use in these patients, explains Heather Gordish-Dressman, Ph.D., a statistician at the Center for Genetic Medicine Research at Children’s National Health System and study senior author. The lack of long-term data led some physicians to delay treatment with these drugs since their use can lead to significant side effects, including weight gain, delayed growth and immunosuppression.

“Everyone had the idea that long-term use could be beneficial, but nobody had really rigorously tested that,” Gordish-Dressman says.

Craig McDonald, M.D., a University of California, Davis, professor and lead author of the study adds: “This long-term, follow-up study provides the most definitive evidence that the benefits of glucocorticoid steroid therapy in DMD extend over the entire lifespan. Most importantly, patients with Duchenne using glucocorticoids experienced an overall reduction in risk of death by more than 50 percent.”

To determine whether the short-term benefits of these drugs extend in the long term, Gordish-Dressman and researchers scattered across the country tapped data from the Cooperative International Neuromuscular Research Group’s Duchenne Natural History Study, the largest study to follow patients with DMD over time. They gathered data for 440 males with DMD aged 2 to 8 years old. About 22 percent had never taken glucocorticoids or had taken these medications for less than one year. The remainder had taken them for at least one year or longer.

By analyzing data for up to 10 years for these patients, the long-term benefits became clear, Gordish-Dressman adds. Glucocorticoid treatment for patients who received it for more than one year delayed loss of mobility milestones that affected the lower limbs by 2.1 to 4.4 years, such as going from supine to standing, climbing four stairs, and walking or running 10 meters, compared with boys who received the medications for less than one year. Long-term glucocorticoid therapy also delayed the loss of mobility milestones in upper limbs, such as hand function, performing a full overhead reach and raising the hands to the mouth.

Long-term use of these drugs also was associated with a decreased risk of death over the length of the study. Furthermore, deflazacort – a glucocorticoid recently approved by the Food and Drug Administration specifically for DMD – delayed loss of the ability to move from supine position to standing, walking and hand-to-mouth function significantly better than prednisone, the most popular glucocorticoid prescribed for DMD in the United States.

Gordish-Dressman says that glucocorticoids are currently a standard part of care for most patients with DMD, with some clinics prescribing these medications as soon as patients are diagnosed. However, because long-term data supporting their use was lacking, some physicians hesitate to prescribe glucocorticoids until the disease had progressed, when patients already had lost significant function.

Future studies will examine which medicines in this class of drugs and which regimens might offer the most benefits as well as how benefits differ with longer-term medication use.

Research reported in this news release was supported by the U.S. Department of Education/NIDRR, H133B031118 and H133B090001; the U.S. Department of Defense, W81XWH-12-1-0417; National Institute of Arthritis and Musculoskeletal and Skin Diseases of the National Institutes of Health under award number R01AR061875; and Parent Project Muscular Dystrophy.

Liquid biopsy spots aggressive brainstem cancer earlier

November 20, 2017

A Children’s National research team led by Javad Nazarian, Ph.D., M.S.C., tested whether circulating tumor DNA in patients’ blood and cerebrospinal fluid would provide an earlier warning that pediatric brainstem tumors were growing.

A highly aggressive pediatric brain cancer can be spotted earlier and reliably by the genetic fragments it leaves in biofluids, according to a study presented by Children’s National Health System researchers at the Society for Neuro-Oncology (SNO) 2017 Annual Meeting. The findings may open the door to non-surgical biopsies and a new way to tell if these tumors are responding to treatment.

Children diagnosed with diffuse midline histone 3 K27M mutant (H3K27M) glioma face a poor prognosis with a median survival time of only nine months after the pediatric brainstem cancer is diagnosed. Right now, clinicians rely on magnetic resonance imaging (MRI) to gauge how tumors are growing, but MRI can miss very small changes in tumor size. The Children’s research team led by Javad Nazarian, Ph.D., M.S.C., scientific director of Children’s Brain Tumor Institute, tested whether circulating tumor DNA in patients’ blood and cerebrospinal fluid would provide an earlier warning that tumors were growing. Just as a detective looks for fingerprints left at a scene, the new genetic analysis technique can detect telltale signs that tumors leave behind in body fluids.

“We continue to push the envelope to find ways to provide hope for children and families who right now face a very dismal future. By identifying these tumors when they are small and, potentially more responsive to treatment, our ultimate aim is to help children live longer,” says Eshini Panditharatna, B.A., study lead author. “In addition, we are hopeful that the comprehensive panel of tests we are constructing could identify which treatments are most effective in shrinking these deadly tumors.”

The researchers collected biofluid samples from 22 patients with diffuse intrinsic pontine glioma (DIPG) who were enrolled in a Phase I, Pacific Pediatric Neuro-Oncology Consortium clinical trial. Upfront and longitudinal plasma samples were collected with each MRI at various stages of disease progression. The team developed a liquid biopsy assay using a sensitive digital droplet polymerase chain reaction system that precisely counts individual DNA molecules.

“We detected H3K27M, a major driver mutation in DIPG, in about 80 percent of cerebrospinal fluid and plasma samples,” Panditharatna says. “Similar to adults with central nervous system (CNS) cancers, cerebrospinal fluid of children diagnosed with CNS cancers has high concentrations of circulating tumor DNA. However, after the children underwent radiotherapy, there was a dramatic decrease in circulating tumor DNA for 12 of the 15 patients (80 percent) whose temporal plasma was analyzed.”

Nazarian, the study senior author adds: “Biofluids, like plasma and cerebrospinal fluid, are suitable media to detect and measure concentrations of circulating tumor DNA for this type of pediatric glioma. Liquid biopsy has the potential to complement tissue biopsies and MRI evaluation to provide earlier clues to how tumors are responding to treatment or recurring.”

Support for this liquid biopsy study was provided by the V Foundation, Goldwin Foundation, Pediatric Brain Tumor Foundation, Smashing Walnuts Foundation, the Zickler Family Foundation, the Piedmont Community Foundation, the Musella Foundation, the Mathew Larson Foundation and Brain Tumor Foundation for Children.

Advancing cures for pediatric cancer: Highlights from leading Children’s National experts at SIOP 2017

November 14, 2017

In mid-October 2017, nearly 2,000 clinicians, scientists, nurses, health care professionals and cancer patients and survivors gathered in Washington, D.C., for SIOP 2017, the Annual Congress of the International Society of Paediatric Oncology. For four days, attendees heard from world-renowned experts while exchanging ideas and information, all in the name of advancing cures for childhood cancer.

Hosted in the hometown of Children’s National Health System and chaired by Jeffrey Dome, M.D., Ph.D., Vice President of the Center for Cancer and Blood Disorders and Chief of Oncology at Children’s National Health System, more than 20 doctors and nurses from Children’s National made an impact on participants through a series of widely attended sessions and addresses, including:

Symposium lecture on the latest approaches in anti-viral T-cell therapy to improve patient outcomes, given by Catherine Bollard, M.D., M.B.Ch.B.
Keynote lecture on DICER1 mutations in pediatric cancer, given by Ashley Hill, M.D., whose study of a rare childhood lung cancer and gene mutations set the stage for a better understanding of microRNA processing gene mutations in the development of pediatric cancer.
Education session on new therapies for sarcomas, led by AeRang Kim, M.D., Ph.D., and Karun Sharma, M.D., Ph.D., sharing research on new approaches for local control of sarcomas, such as surgery, radiation and other ablative measures.
Education session on new therapies for gliomas, led by Roger J. Packer, M.D., with presentations on immunotherapy from Eugene Hwang, M.D., and targeted therapy by Lindsay Kilburn, M.D.
Podium paper presentation on a new method to measure cancer treatment toxicities as reported by the child by Pamela Hinds, Ph.D., RN, FAAN, as well as an education session on advanced care planning, led by Hinds with a presentation from Maureen E. Lyon, Ph.D.

“These sessions and lectures provided a glimpse into the groundbreaking work by SIOP attendees from around the world,” says Dr. Dome. “Children’s National is proud to play an active role in the development of life-saving treatments for children with cancer and our clinicians look forward to another year of revolutionary developments.”

For more on this year’s SIOP, see the Children’s National press release.

Jeffrey Dome, M.D., Ph.D., addresses a group of international colleagues at a reception at Children’s National.
Catherine Bollard, M.D., M.B.Ch.B., addresses a group of international colleagues at a reception at Children’s National.
Lindsay Kilburn, M.D., engages with peers from around the world at a reception at Children’s National.

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Children’s National experts contribute to new Zika guidelines

October 23, 2017

Roberta DeBiasi, M.D., M. S., and Sarah B. Mulkey, M.D., Ph.D., members of Children’s multidisciplinary Congenital Zika Virus Program, were among the experts invited to participate in a forum held in Atlanta at CDC headquarters in late August to formulate new Zika recommendations.

The Centers for Disease Control and Prevention (CDC) on Oct. 19, 2017 updated guidelines for evaluation of women, fetuses and infants exposed to the Zika virus during pregnancy. Although only women with symptoms will now be routinely tested, asymptomatic and symptomatic infants born to these women will still be tested for the Zika virus using blood and urine tests.

Infants who appear normal, whose mothers either had negative Zika results or who had not undergone testing, will not undergo Zika testing. These infants still will undergo a standard evaluation, including a detailed physical exam, hearing screen and routine developmental assessments. The revised Zika guidance includes input from practitioners on the front lines of the Zika epidemic, including Children’s National Health System clinicians.

“These changes in the recommendations for Zika testing should not be interpreted as Zika infection risks subsiding for pregnant women and their infants in the United States. It’s simply an acknowledgement of the limitations of current testing methods – which must occur within a narrow window after Zika exposure – and the poor predictive value of Zika testing right now,” says Roberta L. DeBiasi, M.D., M.S., chief of Children’s Division of Pediatric Infectious Diseases. Dr. DeBiasi and Sarah B. Mulkey, M.D., Ph.D., members of Children’s multidisciplinary Congenital Zika Virus Program, were among the experts invited to participate in the Zika forum held in Atlanta at CDC headquarters in late August to formulate the recommendations.

While all infants will receive a standard evaluation, expanded evaluations that include an ophthalmologic assessment, more detailed hearing evaluation and ultrasound of the newborn’s head will be reserved for infants born to mothers confirmed to be Zika positive or Zika probable, or for infants born with abnormalities potentially consistent with congenital Zika syndrome, regardless of maternal status.

The majority of U.S. infants who have been exposed to Zika in the womb appeared normal at birth, according to CDC registries. Now, the next wave of these normal-appearing babies will receive standard evaluations when they are born, including a newborn hearing screening. At each well-child visit, these infants will receive:

A comprehensive physical examination
An age-appropriate vision screening
Developmental monitoring and screening using validated tools

“This is a natural evolution in the diagnosis and screening strategy now that the peak of the first wave of Zika transmission appears to be over,” Dr. DeBiasi says. “While we continue to evaluate new possible cases of Zika infection among pregnant women in our practice, a sizable proportion of Children’s cases are Zika-exposed infants whose physical exam and neuroimaging appeared normal at birth. Through ongoing monitoring, we hope to learn more about these children’s long-term neurodevelopment outcomes.”

Improving treatment success for Duchenne muscular dystrophy

October 20, 2017

Macrophages, white blood cells involved in inflammation, readily take up a new medicine for Duchenne muscular dystrophy and promote its sustained delivery to regenerating muscle fibers long after the drug has disappeared from circulation.

Chronic inflammation plays a crucial role in the sustained delivery of a new type of muscular dystrophy drug, according to an experimental model study led by Children’s National Health System.

The study, published online Oct. 16, 2017 in Nature Communications, details the cellular mechanisms of morpholino antisense drug delivery to muscles. Macrophages, white blood cells involved in inflammation, readily take up a new medicine for Duchenne muscular dystrophy (DMD) and promote its sustained delivery to regenerating muscle fibers long after the drug has disappeared from circulation.

Until recently, the only approved medicines for DMD targeted its symptoms, rather than the root genetic cause. However, in 2016 the Food and Drug Administration approved the first exon-skipping medicine to restore dystrophin protein expression in muscle: Eteplirsen, an antisense phosphorodiamidate morpholino oligomer (PMO). The drug had shown promise in preclinical studies but had variable and sporadic results in clinical trials.

The Children’s National study adds to the understanding of how this type of medicine targets muscle tissue and suggests a path to improve treatments for DMD, which is the most common and severe form of muscular dystrophy and currently has no cure, explains study co-leader James S. Novak, Ph.D., a principal investigator in Children’s Center for Genetic Medicine Research.

Because the medication vanishes from the blood circulation within hours after administration, Children’s research efforts have focused on the mechanism of delivery to muscle and on ways to increase its cellular uptake – and, by extension, its effectiveness. However, researchers understand little about how this medication actually gets delivered to muscle fibers or how the disease pathology impacts this process, knowledge that could offer new ways of boosting both its delivery and effectiveness, says Terence Partridge, Ph.D., study co-leader and principal investigator in Children’s Center for Genetic Medicine Research.

To investigate this question, Novak, Partridge and colleagues used an experimental model of DMD that carries a version of the faulty DMD gene that, like its human counterparts, destroys dystrophin expression. To track the route of the PMO into muscle fibers, they labeled it with a fluorescent tag. The medicine traveled to the muscle but only localized to patches of regenerating muscle where it accumulated within the infiltrating macrophages, immune cells involved in the inflammatory response that accompanies this process. While PMO is rapidly cleared from the blood, the medication remained in these immune cells for up to one week and later entered muscle stem cells, allowing direct transport into regenerating muscle fibers. By co-administering the PMO with a traceable DNA nucleotide analog, the research team was able to define the stage during the regeneration process that promotes heightened uptake by muscle stem cells and efficient dystrophin expression in muscle fibers.

“These macrophages appear to extend the period of availability of this medication to the satellite cells and muscle fibers at these sites,” Partridge explains. “Since the macrophages are acting as long-term storage reservoirs for prolonged delivery to muscle fibers, they could possibly represent new therapeutic targets for improving the uptake and delivery of this medicine to muscle.”

Future research for this group will focus on testing whether macrophages might be used as efficient delivery vectors to transport eteplirsen to the muscle, which would avert the rapid clearance currently associated with intravenous delivery.

“Understanding exactly how different classes of exon-skipping drugs are delivered to muscle could open entirely new possibilities for improving future therapeutics and enhancing the clinical benefit for patients,” Novak adds.

What Children’s has learned about congenital Zika infection

October 18, 2017

Roberta DeBiasi, M.D., M.S., outlined lessons learned during a pediatric virology workshop at IDWeek2017, one of three such Zika presentations led by Children’s National research-clinicians during this year’s meeting of pediatric infectious disease specialists.

The Congenital Zika Virus Program at Children’s National Health System provides a range of advanced testing and services for exposed and infected fetuses and newborns. Data that the program has gathered in evaluating and managing Zika-affected pregnancies and births may offer instructive insights to other centers developing similar programs.

The program evaluated 36 pregnant women and their fetuses from January 2016 through May 2017. Another 14 women and their infants were referred to the Zika program for postnatal consultations during that time.

“As the days grow shorter and temperatures drop, we continue to receive referrals to our Zika program, and this is a testament to the critical need it fulfills in the greater metropolitan D.C. region,” says Roberta L. DeBiasi, M.D., M.S., chief of the Division of Pediatric Infectious Diseases and co-leader of the program. “Our multidisciplinary team now has consulted on 90 dyads (mothers and their Zika-affected fetuses/infants). The lessons we learned about when and how these women were infected and how their offspring were affected by Zika may be instructive to institutions considering launching their own programs.”

Dr. DeBiasi outlined lessons learned during a pediatric virology workshop at IDWeek2017, one of three such Zika presentations led by Children’s National research-clinicians during this year’s meeting of pediatric infectious disease specialists.

“The Zika virus continues to circulate in dozens of nations, from Angola to the U.S. Virgin Islands. Clinicians considering a strategic approach to managing pregnancies complicated by Zika may consider enlisting an array of specialists to attend to infants’ complex care needs, including experts in fetal imaging, pediatric infectious disease, physical therapists, audiologists, ophthalmologists and radiologists skilled at reading serial magnetic resonance images as well as ultrasounds,” Dr. DeBiasi says. “At Children’s we have a devoted Zika hotline to triage patient and family concerns. We provide detailed instructions for referring institutions explaining protocols before and after childbirth, and we provide continuing education for health care professionals.”

Of the 36 pregnant women possibly exposed to Zika during pregnancy seen in the program’s first year, 32 lived in the United States and traveled to countries where Zika virus was circulating. Two women had partners who traveled to Zika hot zones. And two moved to the Washington region from places where Zika is endemic. Including the postnatal cases, 89 percent of patients had been bitten by Zika-tainted mosquitoes, while 48 percent of women could have been exposed to Zika via sex with an infected partner.

Twenty percent of the women were exposed before conception; 46 percent were exposed to Zika in the first trimester of pregnancy; 26 percent were exposed in the second trimester; and 8 percent were exposed in the final trimester. In only six of 50 cases (12 percent) did the Zika-infected individual experience symptoms.

Zika infection can be confirmed by detecting viral fragments but only if the test occurs shortly after infection. Twenty-four of the 50 women (nearly 50 percent) arrived for a Zika consultation outside that 12-week testing window. Eleven women (22 percent) had confirmed Zika infection and another 28 percent tested positive for the broader family of flavivirus infections that includes Zika. Another detection method picks up antibodies that the body produces to neutralize Zika virus. For seven women (14 percent), Zika infection was ruled out by either testing method.

“Tragically, four fetuses had severe Zika-related birth defects,” Dr. DeBiasi says. “Due to the gravity of those abnormalities, two pregnancies were not carried to term. The third pregnancy was carried to term, but the infant died immediately after birth. The fourth pregnancy was carried to term, but that infant survived less than one year.”

Antioxidants could thwart muscle repair

September 6, 2017

Science Signaling features a Research Article that describes the pathway by which mitochondria transduce the increase in cytosolic Ca2+ caused by plasma membrane injury into a ROS-dependent repair response. The image shows ROS production and actin polymerization as detected by fluorescent reporters near a plasma membrane injury site in a skeletal myofiber in an intact bicep of an experimental model. Credit: Adam Horn and Jyoti Jaiswal, M.S.C., Ph.D. Children’s National Health System and The George Washington University School of Medicine and Health Sciences

Reactive oxygen species (ROS) are a biological double-edged sword. These atoms, molecules or molecular fragments containing oxygen that is poised for chemical reactions, are a key part of the immune response, used by immune cells to kill potentially dangerous invaders such as bacteria. However, too much ROS – which also are produced as a normal part of cellular metabolism – can cause extreme damage to normal, healthy cells.

Because oxidative damage has been linked with cancer, many people make a concerted effort to consume antioxidants in food and as concentrated supplements. These compounds can neutralize ROS, stemming cellular damage. Taking antioxidants also has been thought to stem the muscle soreness from exercise since ROS are produced in excess during hard physical activity.

However, a new study led by researchers from Children’s National Health System finds that taking antioxidants could thwart the processes that repair muscle fibers. According to the study published Sept. 5, 2017 in Science Signaling and featured on the journal’s cover, oxidative species are crucial signals that start the process of repairing muscle fibers.

Cellular powerhouses known as mitochondria help injured muscle cells (myofibers) repair by soaking up calcium that enters from the site of injury and using it to trigger increased production of reactive oxygen species. Loading up mitochondria with excess antioxidants inhibits this signaling process, blocking muscle repair, exacerbating myofiber damage and diminishing muscle strength.

“Our results suggest a physiological role for mitochondria in plasma membrane repair in injured muscle cells, a role that highlights a beneficial effect of reactive oxygen species,” says Jyoti K. Jaiswal, M.S.C., Ph.D., principal investigator in the Center for Genetic Medicine Research at Children’s National Health System, associate professor of genomics and precision medicine at The George Washington University School of Medicine and Health Sciences and senior study author. “Our work highlights the need to take a nuanced view of the role of reactive oxygen species, as they are necessary when they are present at the right place and right time. Indiscriminate use of antioxidants actually could harm an adult with healthy muscles as well as a child with diseased muscle.”

Antioxidants are widely used by Baby Boomers with muscles that ache from a grueling workout or newborns diagnosed with muscular dystrophy. Jaiswal and Children’s National colleagues understand that their results buck conventional wisdom that antioxidants generally benefit muscle recovery.

“It is still a common belief within the fitness community that taking antioxidant supplements after a workout will help your muscles recover better. That’s what people think; that’s what I thought,” says Adam Horn, lead study author, a graduate student at The George Washington University who works with Jaiswal at Children’s National. “What we’ve done is figure out that mitochondria need to produce a very specific oxidative signal in response to muscle damage in order to help injured muscles repair.”

The oxidative signals produced by mitochondria are delicately balanced by the antioxidant defenses in healthy cells. This balance can be disrupted in diseases such as Duchenne muscular dystrophy, which is caused by the lack of a muscle-specific protein, dystrophin. Lack of dystrophin makes the muscle cell plasma membrane more vulnerable to injury. In an experimental model of Duchenne muscular dystrophy, the muscles at birth are seemingly normal but, within weeks, show obvious muscle damage and progressive weakness.

“What changes? One of the things that changes in the third and fourth week of life of this experimental model is mitochondrial functionality,” Jaiswal adds. “They end up with many dysfunctional mitochondria, which compromise repair of injured myofibers. This permits chronic and excessive oxidation of the myofibers and disruption of the proper oxidant-antioxidant balance.”

In this case, a dose of antioxidants may restore that proper balance and help to reverse muscle damage and progressive weakness.

As a next step, the research team is examining oxidation in healthy and diseased muscle to understand how the oxidant-antioxidant balance is disrupted and how it could be restored efficiently by using existing supplements. In one such study funded by the National Institutes of Health, the team is looking at the potential benefit of vitamin E supplements for patients with muscular dystrophy.

“Antioxidant supplements are made from extracts of bark, sap, chocolate and other compounds so they’re all different,” Jaiswal says. “Knowing which ones can restore balance under a specific circumstance has the potential to help the body maintain proper cellular signaling ability, which will keep muscles healthy and working properly.”

The response of actin protein following injury to a pair of muscle fibers in an intact biceps muscle.

Advancing pediatric cancer research by easing access to data

August 23, 2017

“This is a tremendous opportunity for children and families whose lives have been forever altered by pediatric cancers,” says Javad Nazarian, Ph.D., M.S.C., principal investigator in the Center for Genetic Medicine Research and scientific director of the Brain Tumor Institute at Children’s National.

Speeding research into pediatric cancers and other diseases relies not only on collecting good data, but making them accessible to research teams around the world to analyze and build on. Both efforts take time, hard work and a significant amount of financial resources – the latter which can often be difficult to attain.

In a move that could considerably advance the field of pediatric cancer, the National Institutes of Health (NIH), a body that funds biomedical research in the United States, recently awarded a public-private research collective that includes Children’s National Health System up to $14.8 million to launch a data resource center for cancer researchers around the world in order to accelerate the discovery of novel treatments for childhood tumors. Contingent on available funds, five years of funding will be provided by the NIH Common Fund Gabriella Miller Kids First Pediatric Research Program, named after Gabriella Miller, a 10-year-old child treated at Children’s National.

As principal investigators, researchers at Children’s Hospital of Philadelphia will lead the joint effort to build out the “Kids First” Data Resource Center. Children’s National in Washington, D.C., will spearhead specific projects, including the Open DIPG project, and as project ambassador will cultivate additional partnerships with public and private foundations and related research consortia to expand a growing trove of data about pediatric cancers and birth defects.

“This is a tremendous opportunity for children and families whose lives have been forever altered by pediatric cancers,” says Javad Nazarian, Ph.D., M.S.C., principal investigator in the Center for Genetic Medicine Research and scientific director of the Brain Tumor Institute at Children’s National. “From just a dozen samples seven years ago, Children’s National has amassed one of the nation’s largest tumor biorepositories funded, in large part, by small foundations. Meanwhile, research teams have been sequencing data from samples here and around the world. With this infusion of federal funding, we are poised to turn these data into insights and to translate those research findings into effective treatments.”

Today’s NIH grant builds on previous funding that Congress provided to the NIH Common Fund to underwrite research into structural birth defects and pediatric cancers. In the first phase, so-called X01 grantees—including Eric Vilain, M.D., Ph.D., newly named director of the Center for Genetic Medicine Research at Children’s National—received funding to sequence genetic data from thousands of patients and families affected by childhood cancer and structural birth defects.

This new phase of funding is aimed at opening access to those genetic sequences to a broader group of investigators around the globe by making hard-to-access data easily available on the cloud. The first project funded will be Open DIPG, run by Nazarian, a single disease prototype demonstrating how the new data resource center would work for multiple ailments.

DIPG stands for diffuse intrinsic pontine glioma, aggressive pediatric brain tumors that defy treatment and are almost always fatal. Just as crowd sourcing can unleash the collective brainpower of a large group to untangle a problem swiftly, open data sharing could accomplish the same for childhood cancers, including DIPG. In addition to teasing out molecular alterations responsible for making such cancers particularly lethal, pooling data that now sits in silos could help to identify beneficial mutations that allow some children to survive months or years longer than others.

“It’s a question of numbers,” Dr. Vilain says. “The bottom line is that making sense of the genomic information is significantly increased by working through large consortia because they provide access to many more patients with the disease. What is complicated about genetics is we all have genetic variations. The challenge we face is teasing apart regular genetic variations from those genetic variations that actually cause childhood cancers, including DIPG.”

Nazarian predicts some of the early steps for the research consortium will be deciding nuts-and-bolts questions faced by such a start-up venture, such as the best methods to provide data access, corralling the resources needed to store massive amounts of data, and providing data access and cross correlation.

“One of the major challenges that the data resource center will face is to rapidly establish physical data storage space to store all of the data,” Nazarian says. “We’re talking about several petabytes—1,000 terabytes— of data. The second challenge to address will be data dissemination and, specifically, correlation of data across platforms representing different molecular profiles (genome versus proteome, for example). This is just the beginning, and it is fantastic to see a combination of public and private resources in answering these challenges.”

Mitochondria key for repairing cell damage in DMD

August 16, 2017

A research team led by Jyoti K. Jaiswal, M.S.C., Ph.D., found that dysfunctional mitochondria prevent repair of muscle cells in Duchenne muscular dystrophy.

PDF Version

What’s known

Duchenne muscular dystrophy (DMD), one of the most severe forms of muscular dystrophy, is caused by a defect in the dystrophin gene. The protein that this gene encodes is responsible for anchoring muscle cells’ inner frameworks, or cytoskeletons, to proteins and other molecules outside these cells, the extracellular matrix. Without functional dystrophin protein, the cell membranes of muscle cells become damaged, and the cells eventually die. This cell death leads to the progressive muscle loss that characterizes this disease. Why these cells are unable to repair this progressive damage has been unknown.

What’s new

A research team led by Jyoti K. Jaiswal, M.S.C., Ph.D., a principal investigator in the Center for Genetic Medicine Research at Children’s National Health System, investigated this question in two experimental models of DMD that carry different mutations of the dystrophin gene. The researchers monitored the effects of the lack of functional dystrophin protein in these preclinical models on the level and function of muscle cell. They found that mitochondria – organelles that act as powerhouses to supply the chemical energy to drive cellular activities – are among the first to be affected. They found that the decline in mitochondrial level and activity over time in these experimental models preceded the onset of symptoms. The research team also looked at the ability of the experimental models’ muscle cells to repair damage. As the muscle cell mitochondria lost function, the cells’ ability to repair damage also declined. Efforts to increase mitochondrial activity after these organelles became dysfunctional did not improve muscle repair. This suggests that poor muscle repair may not be caused by a deficit in energy production by mitochondria.

Questions for future research

Q: Does similar mitochondrial dysfunction occur in human patients with DMD?
Q: How can the mitochondrial dysfunction be prevented?
Q: Is there a way to reverse mitochondrial dysfunction to better preserve the ability of muscle cells to repair from DMD-related damage?

Source: “Mitochondria mediate cell membrane repair and contribute to Duchenne muscular dystrophy.” Vila, M.C., S. Rayavarapu, M.W. Hogarth, J.H. Van der Meulen, A. Horn, A. Defour, S. Takeda, K.J. Brown, Y. Hathout, K. Nagaraju and J.K. Jaiswal. Published by Cell Death and Differentiation February 2017.

Lab led by Zhe Han, Ph.D., receives $1.75 million from NIH

July 31, 2017

A new four-year NIH grant will enable Zhe Han, Ph.D., to carry out the latest stage in the detective work to determine how histone-modifying genes regulate heart development and the molecular mechanisms of congenital heart disease caused by these genetic mutations.

The National Institutes of Health (NIH) has awarded $1.75 million to a research lab led by Zhe Han, Ph.D., principal investigator and associate professor in the Center for Genetic Medicine Research, in order to build models of congenital heart disease (CHD) that are tailored to the unique genetic sequences of individual patients.

Han was the first researcher to create a Drosophila melanogaster model to efficiently study genes involved in CHD, the No.1 birth defect experienced by newborns, based on sequencing data from patients with the heart condition. While surgery can fix more than 90 percent of such heart defects, an ongoing challenge is how to contend with the remaining cases since mutations of a vast array of genes could trigger any individual CHD case.

In a landmark paper published in 2013 in the journal Nature, five different institutions sequenced the genomes of more than 300 patients with CHD and their families, identifying 200 mutated genes of interest.

“Even though mutations of these genes were identified from patients with CHD, these genes cannot be called ‘CHD genes’ since we had no in vivo evidence to demonstrate these genes are involved in heart development,” Han says. “A key question to be answered: How do we efficiently test a large number of candidate disease genes in an experimental model system?”

In early 2017, Han published a paper in Elife providing the answer to that lingering question. By silencing genes in a fly model of human CHD, the research team confirmed which genes play important roles in development. The largest group of genes that were validated in Han’s study were histone-modifying genes. (DNA winds around the histone protein, like thread wrapped around a spool, to become packed into a higher-level structure.)

The new four-year NIH grant will enable Han to carry out the next stage of the detective work to determine precisely how histone-modifying genes regulate heart development. In order to do so, his group will silence the function of histone-modifying genes one by one, to study their function in the fly heart development and to identify the key histone-modifying genes for heart development. And because patients with CHD can have more than one mutated gene, he will silence multiple genes simultaneously to determine how those genes work in partnership to cause heart development to go awry.

By the end of the four-year research project, Han hopes to be able to identify all of the histone-modified genes that play pivotal roles in development of the heart in order to use those genes to tailor make personalized fly models corresponding to individual patient’s genetic makeup.

Parents with mutations linked to CHD are likely to pass heart disease risk to the next generation. One day, those parents could have an opportunity to sequence their genes to learn the degree of CHD risk their offspring face.

“Funding this type of basic research enables us to understand which genes are important for heart development and how. With this knowledge, in the near future we could predict the chances of a baby being born with CHD, and cure it by using gene-editing approaches to prevent passing disease to the next generation,” Han says.

Understanding genetic synergy in cleft palate

July 19, 2017

Like mechanics fixing a faulty engine, Youssef A. Kousa, M.S., D.O., Ph.D., says researchers will not be able to remedy problems related to IRF6, a gene implicated in cleft palate, until they better understand how the gene works.

Like all of the individual elements of fetal development, palate growth is a marvel of nature. In part of this process, ledges of tissue on the sides of the face grow downwards on each side of the tongue, then upward, fusing at the midline at the top of the mouth. The vast majority of the time, this process goes correctly. However, some part of it goes awry for the 2,650 babies born in the United States each year with cleft palates and the thousands more born worldwide with the defect.

For nearly two decades, researchers have known that a gene known as IRF6 is involved in palate formation. Studies have shown that this gene contributes about 12 percent to 18 percent of the risk of cleft palate, more than any other gene identified thus far. IRF6 is active in epithelial tissues – those that line cavities and surfaces throughout the body – including the periderm, a tissue that lines the mouth cavity and plays an important role during development.

According to Youssef A. Kousa, M.S., D.O., Ph.D., a child neurology fellow at Children’s National Health System, the periderm acts like a nonstick layer, preventing the tongue or other structures from adhering to the growing palate and preventing it from sealing at the midline. While researchers have long suspected that IRF6 plays a strong role in promoting this nonstick quality, exactly how it exerts its influence has not been clear.

“Gaining a better understanding of this gene might help us to eventually address deficits or perturbations in the system that creates the palate,” Dr. Kousa says. “Like a mechanic fixing a faulty engine, we will not be able to remedy problems related to this gene until we know how the gene works.”

“Gaining a better understanding of this gene might help us to eventually address deficits or perturbations in the system that creates the palate,” Dr. Kousa says. “Like a mechanic fixing a faulty engine, we will not be able to remedy problems related to this gene until we know how the gene works.”

In a study published July 19, 2017 by the Journal of Dental Research, Dr. Kousa and colleagues seek to decipher one piece of this puzzle by investigating how this key gene might interact with others that are active during fetal development. The researchers were particularly interested in genes that work together in a cascade of activity known as the tyrosine kinase receptor signaling pathway.

Because this pathway includes a large group of genes, Dr. Kousa and colleagues reasoned that they could answer whether IRF6 interacts with this pathway by looking at whether the gene interacts with the last member of the cascade, a gene called SPRY4. To do this, the researchers worked with experimental models that had mutations in IRF6, SPRY4 or both. If these two genes interact, the scientists hypothesized, carrying mutations in both genes at the same time should result in a dramatically different outcome compared with animals that carried mutations in just one gene.

Using selective breeding techniques, the researchers created animals that had mutations in either of these genes or in both. Their results suggest that IRF6 and SPRY4 indeed do interact: Significantly more of the oral surface was adhered to the tongue during fetal development in experimental models that had mutations in both genes compared with those that had just one single gene mutated. Examining the gene activity in the periderm cells of these affected animals, the researchers found that doubly mutated experimental models also had decreased activity in a third gene known as GRHL3, which also has been linked with cleft lip and palate.

Dr. Kousa says the research team plans to continue exploring this interaction to better understand the flow of events that lead from perturbations in these genes to formation of cleft palate. Some of the questions they would like to answer include exactly which gene or genes in the tyrosine kinase receptor signaling pathway specifically interact with IRF6 – since SPRY4 represents just the end of that pathway, others genes earlier in the pathway are probably the real culprits responsible for driving problems in palate formation. They also will need to verify if these interactions take place in humans in the same way they occur in preclinical models.

Eventually, Dr. Kousa adds, the findings could aid in personalized prenatal counseling, diagnosis and screening related to cleft palate, as well as preventing this condition during pregnancy. Someday, doctors might be able to advise couples who carry mutations in these genes about whether they are more likely to have a baby with a cleft palate or determine which select group of pregnancies need closer monitoring. Additionally, because research suggests that GRHL3 might interact with nutrients, including inositol, it might be possible to prevent some cases of cleft palate by taking additional supplements during pregnancy.

“The more we know about how these genes behave,” Dr. Kousa says, “the more we can potentially avoid fetal palate development going down the wrong path.”