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Robert J. Freishtat working in the lab

Detecting early signs of type 2 diabetes through microRNA

Robert J. Freishtat working in the lab

Obesity is a major risk factor for insulin resistance and type 2 diabetes. Now researchers understand the pathogenesis better among teens with mid-level obesity, thanks to clues released from circulating adipocyte-derived exosomes.

Researchers know that exosomes, tiny nanoparticles released from fat cells, travel through the bloodstream and body, regulating a variety of processes, from growth and development to metabolism. The exosomes are important in lean, healthy individuals in maintaining homeostasis, but when fat gets ‘sick’ – the most common reason for this is too much weight gain – it can change its phenotype, becoming inflammatory, and disrupts how our organs function, from how our skeletal muscle and liver metabolize sugar to how our blood vessels process cholesterol.

Robert J. Freishtat, M.D., M.P.H., the chief of emergency medicine at Children’s National Health System and a professor of precision medicine and genomics at the George Washington University School of Medicine and Health Sciences, and Sheela N. Magge M.D., M.S.C.E., who is now the director of pediatric endocrinology and an associate professor of medicine at the Johns Hopkins School of Medicine, were curious about what this process looked like in teens who fell in the mid-range of obesity.

Obesity is a major risk factor for insulin resistance and type 2 diabetes, but Dr. Freishtat and Dr. Magge wanted to know: Why do some teens with obesity develop type 2 diabetes over others? Why are some teens in this mid-range of obesity metabolically healthy while others have metabolic syndrome? Can fat in obese people become sick and drive disease?

To test this, Dr. Freishtat and Dr. Magge worked with 55 obese adolescents, ages 12 to 17, as part of a study at Children’s National. The participants – 32 obese normoglycemic youth and 23 obese hyperglycemic youth – were similar in age, sex, race, pubertal stage, body mass index and overall fat mass. The distinguishing factor: The hyperglycemic study participants, the teens with elevated blood sugar, differed in where they stored fat. They had extra visceral fat (or adipose tissue) storage, the type of fat that surrounds the liver, pancreas and intestines, a known risk factor for type 2 diabetes.

Dr. Magge and Dr. Freishtat predicted that circulating exosomes from the teens with elevated blood sugar are enriched for microRNAs targeting carbohydrate metabolism.

They used three tests to examine study participants’ metabolism, body composition and circulating exosomes. The first test, an oral glucose tolerance test, measures how efficiently the body metabolizes sugar; the second test is the whole body DXA, or dual-energy x-ray absorptiometry, which analyzes body composition, including lean tissue, fat mass and bone mineral density; and the third test, the serum adipocyte-derived exosomal microRNA assays, is an analysis of circulating fat signals in the bloodstream.

They found that teens with elevated blood sugar and increased visceral fat had different circulating adipocyte-derived exosomes. These study participants’ exosomes were enriched for 14 microRNAs, targeting 1,304 mRNAs and corresponding to 179 canonical pathways – many of which are directly associated with carbohydrate metabolism and visceral fat.

Dr. Magge will present this research, entitled “Changes in Adipocyte-Derived Exosomal MicroRNAs May Play a Role in the Progression from Obese Normoglycemia to Hyperglycemia/Diabetes,” as an oral abstract at the American Diabetes Association’s 79th Scientific Sessions on Saturday, June 8.

Dr. Freishtat envisions having this information will be especially helpful for a patient in a mid-range of obesity. Exosomes primarily consist of small non-coding RNAs. In the current study, the altered RNAs affect P13K/AKT and STAT3 signaling, vital pathways for metabolic and immune function.

“Instead of waiting until someone has the biochemical changes associated with type 2 diabetes, such as hyperglycemia, hyperlipidemia and insulin resistance, we’re hoping physicians will use this information to work with patients earlier,” says Dr. Freishtat. “Through earlier detection, clinicians can intervene when fat shows sign of illness, as opposed to when the overt disease has occurred. This could be intervening with diet and lifestyle for an obese individual or intervening with medication earlier. The goal is to work with children and teens when their system is more plastic and responds better to intervention.”

As this research evolves, Dr. Freishtat continues to look at the intergenerational effects of circulating adipocyte-derived exosomes. Through ongoing NIH-funded research in India, he finds these exosomes, similar in size to lipoproteins, can travel across the placenta, affecting development of the fetus in utero.

“What we’re finding in our initial work is that these exosomes, or ‘sick’ fat, cross the placenta and affect fetal development,” Dr. Freishtat says. “Some of the things that we’re seeing are a change in body composition of the fetus to a more adipose phenotype. Some of our work in cell cultures shows changes in stem cell function and differentiation, but what’s even more interesting to us is that if the fetus is a female sex that means her ovaries are developing while she’s in utero, which means a mother’s adipocyte-derived exosomes could theoretically be affecting her grandchild’s phenotype – influencing the health of three generations.”

While this research is underway, Dr. Freishtat is working with JPOD @ Boston, co-located with the Cambridge Innovation Center in Cambridge, Massachusetts, to develop a test to provide analyses of adipocyte-derived exosomal microRNAs.

“It’s important for families to know that these studies are designed to help researchers and doctors better understand the development of disease in its earliest stages, but there’s no need for patients to wait for the completion of our studies,” says Dr. Freishtat. “Reaching and maintaining a healthy body weight and exercising are important things teens and families can do today to reduce their risk for obesity and diabetes.”

M and her daughter

Tracing the history of aggrecan gene mutations

M and her daughter

M takes a photo with her daughter in Washington, where they learned they have an ACAN gene mutation that causes short stature.

On Sunday, April 28, 2019 a team of researchers received the 2019 Human Growth Award at the Pediatric Endocrine Society’s Annual Meeting for their abstract, entitled “Clinical Characterization and Trial of Growth Hormone in Patients with Aggrecan Deficiency: 6 Month Data,” and presented this at the PES Presidential Poster Session.

Eirene Alexadrou, M.D., a fellow at Cincinnati Children’s Hospital Medical Center, accepted the award and honorarium, while ongoing research is underway. This study started in 2017, with the objective of characterizing the phenotypic spectrum and response to a standardized regimen of growth hormone in a small cohort of 10 patients and their families.

In 2017, Andrew Dauber, M.D., MMSc., the division chief of endocrinology at Children’s National Health System, led an international consortium of researchers in publishing a manuscript describing the phenotypic spectrum of 103 individuals – 70 adults and 33 children, including 57 females and 46 males – from 20 families with aggrecan gene (ACAN) mutations.

Dr. Dauber and his colleagues have established that short stature and accelerated bone age is common among people with ACAN mutations. In a review of retrospective data, including patients treated with a variety of growth-promoting therapies at varying doses, the research team found that over the first one, two and three years of treatment, the standard deviation scores (SDS) for height increased by .4, .7 and 1, respectively. The current abstract now describes seven children enrolled in a prospective standardized trial of growth hormone therapy. After six months of treatment, the children have increased their height SDS by an average of 0.46.

Additionally, the researchers are performing an in-depth look at the joint effects, including special MRIs of the knees. They found that two of the children had a problem with their knee cartilage called osteochondritis dissecans. They had not yet presented with clinical symptoms. The researchers hope that early intervention with physical therapy can help prevent significant joint disease in the future.

M and her mother and daughter in Cincinnati

M, her daughter, and M’s mother take a photo in Cincinatti, where they are pariticipating in a clinical trial for aggrecan deficiency.

“Providing growth hormone therapy to children with ACAN gene mutations is relatively new in the field of pediatric endocrinology,” notes Dr. Dauber. “Previously, the assumption was that this was just short stature. We’ll continue to diagnose ACAN mutations in a clinical setting and work with families to reduce the risk of complications, such as joint problems or early-onset arthritis, which may co-occur with this gene mutation.”

As an example, Dr. Dauber met an 8-year-old patient several months ago who presented with symptoms of short stature. The patient is healthy, confident and still growing so her mother wasn’t worried about her but she made the appointment to see if there was an underlying cause to her daughter’s short stature. Her family history revealed clues to an ACAN mutation, which was later confirmed through genetic tests. Her mom, M, stands 4’8; her grandmother is 4’9. Her great grandmother was short and her great, great grandfather was 5’1. Short stature and joint problems run in the family. Once M mentioned she had osteochondritis dissecans and a hip replacement, she provided a textbook case study for carrying the ACAN mutation.

After the appointment, M shared the news with her mother about the possibility of having aggrecan deficiency. After taking genetic tests, M, her mother and M’s daughter learned they all have the ACAN mutation, and enrolled in the study that Dr. Dauber is guiding. Suddenly, it all made sense. After examining family photos, they traced the ACAN mutation back through four generations.

They could tell what relatives had an altered copy of the ACAN gene. M had it, while her two sisters did not. M’s mother was an only child, so she didn’t have aunts or uncles to compare her mother’s height to, but M’s grandmother was short, while her grandmother’s brother was average height. Although her mother’s family was from Germany, she learned that there is no specific ancestry associated with this mutation. It happens by chance and is passed down from a single parent to, on average, half of their children, a form of genetic inheritance called autosomal dominant transmission.

Ms great grandmother and grandfather

M’s great grandfather was noticeably shorter than her great grandmother, who was 5’4.

Through further research, M learned that the ACAN gene provides instructions for producing aggrecan protein, which is essential for bone growth, as well as for the stability of cartilage that lines bones and joints, explaining her recurring joint problems.

She also looked into the future, examining potential risk factors for her daughter: joint pain and bone conditions, which could contribute to arthritis, hip dysplasia and back problems.

The diagnosis now makes it easier for M and her daughter to favor bone-building activities that are easy on the joints, like swimming or water aerobics, instead of gymnastics and weight lifting. After having a hip replacement, M was careful to supplement with calcium and vitamin D. Now, she’ll take the same steps to ensure optimal bone health for her daughter. She’ll work with orthopedic specialists as her daughter grows into her pre-teen and adolescent years, carefully monitoring joint pain – altering activities that are tough on the joints, as necessary.

M let her daughter make a decision about growth hormone therapy, which she decided to try. The benefits of the treatment, increased height, carry inconveniences, such as taking daily shots, but they are sticking with it.

“We’re at the tip of the iceberg with research that explores this gene mutation,” says Dr. Dauber. “We’ll continue to study these families, and more, over time to assess growth patterns and  gene expression, which may reveal other mutations associated with short stature or joint problems, and guide future treatment options. It was a coincidence that this family had the ACAN mutation and scheduled an appointment, while we’re conducting this study. Otherwise, they may not have had an answer since this is fairly new research.”

M and her daughter are happy to be part of this study, which they will participate in for the next few years. M’s mother is also glad to participate. She made a different choice, decades ago, to reject hormone treatment when it was offered to her for undiagnosed short stature, but she’s sharing genetic clues, which may influence treatment options for her granddaughter and for her family’s next generation.

The original study, “Clinical Characterization of Patients with Autosomal Dominant Short Stature due to Aggrecan Muations,” appeared in the Feb. 2017 issue of the Journal of Clinical Endocrinology and Metabolism, and published as an online advance on Nov. 21, 2016.

Thirty-six researchers collaborated on this original paper, which was funded by 16 international health institutes and foundations, including the Eunice Kennedy Shriver National Institute of Child Health and Human Development at the National Institutes of Health, the Swedish Research Council, the Swedish Governmental Agency for Innovation Systems, the Marianne and Marcus Wallenberg Foundation, the Stockholm County Council, the Swedish Society of Medicine, Byggmastare Olle Engkvist’s Foundation, the Sao Paulo Research Foundation, the Spanish Ministry of Education and Science, the Czech Health Research Council and the Ministry of Health, Czech Republic.

DNA Molecule

Using genomics to solve a 20-year case study

DNA Molecule

“The advent of different technologies and techniques over the years allowed pieces of her diagnosis to be made – and then brought all together,” says Andrew Dauber, M.D., MMSc.

After 20 years, a patient’s family received an answer to a decades-long genetic mystery. Their daughter had two rare disorders, Angelman syndrome and P450scc deficiency, which was detected after researchers found out she had uniparental disomy, two copies of chromosome 15 from one parent and none from another.

The research paper, entitled “Adrenal Insufficiency, Sex Reversal and Angelman Syndrome due to Uniparental Disomy Unmasking a Mutation in CYP11A1,” was published on March 22, 2018, and recognized as the best novel insight paper published by Hormone Research in Paediatrics in 2018, announced at the Pediatric Endocrine Society’s Annual Meeting in Baltimore on Saturday, April 27, 2019.

By using a variety of genetic tools, including whole-exome sequencing, microarray analyses and in-vitro modeling for gene splicing, the researchers were able to confirm this patient had uniparental disomy, a recessive genetic condition. They learned that after she received two impaired copies of chromosome 15 from her father, this woman developed a hormonal problem that led to adrenal insufficiency and sex reversal. This explained why she physically presented as a female, despite having testes and a Y-chromosome. It also explained other symptoms, including developmental delays and seizures.

“It’s a unique conglomeration of symptoms, manifested by the combination of these two very rare disorders,” says Andrew Dauber, M.D., MMSc., the division chief of endocrinology at Children’s National Health System and a guiding research author of this study. “The advent of different technologies and techniques over the years allowed pieces of her diagnosis to be made – and then brought together, commencing a 20-year diagnostic odyssey.”

For example, each of the conditions this patient has is known and rare: Angelman syndrome affects about one in 10 to 20,000 people in the U.S. Typical symptoms include those observed in this patient: delayed development, intellectual disability, speech impairment and seizures. Side-chain cleavage disorder, which leads to adrenal disorders and sex reversal, is also very rare. In 2005 the chances of survival with a P450scc defect were slim, but since then more than 28 infants have been diagnosed with this gene deficiency, which is required to convert cholesterol to pregnenolone, a hormone in the adrenal gland.

Dr. Dauber notes the chances of this occurring again are highly unlikely. The odds here are one in a gazillion. In this case, one disorder unmasked another, leaving researchers with new insights into the methodology for unraveling ultra-rare genetic disorders or for more common rare conditions.

“Knowing about the gene that caused the adrenal insufficiency and understanding this etiology won’t change medical care for this patient, but it will change the way researchers think about genetic detective work and about combining different technologies,” says Dr. Dauber. “We know that genetic disorders can be complex presentations of different disorders combined. This patient didn’t have one disorder, but three.”

When asked about the significance of the award, Dr. Dauber notes that, “It’s not that other people haven’t recognized this concept before, but this case is a striking example of it. Different technologies will unveil different types of genetic changes, which is why you have to use the right technology or the right technologies in the right combination to piece together the whole picture.”

Ahlee Kim, M.D., the lead study author and a clinical research fellow at Cincinnati Children’s Hospital Medical Center, will receive the award and the honorarium.

Additional study authors include Masanobu Fujimoto, Ph.D., Vivian Hwa, Ph.D., and Philippe Backeljauw, M.D., from Cincinnati Children’s Hospital.

The research was supported by grant K23HD07335, awarded to Dr. Dauber, from the Eunice Kennedy Shriver National Institute of Child Health and Human Development of the National Institutes of Health (NIH). Additional funding included grant 1UL1TR001425 from the NIH’s National Center for Advancing Translational Sciences.

Test tube that says IGF-1 test

A new algorithm: Using genomics and EHR to detect severe growth disorders

Test tube that says IGF-1 test

Andrew Dauber, M.D., MMSc., a pediatric endocrinologist and the chief of endocrinology at Children’s National, guided research presented at ENDO 2019, the Endocrine Society’s annual meeting, enabling clinicians and researchers to understand the genetic underpinnings of certain pediatric growth disorders, while using electronic health record (EHR) algorithms to screen for presenting symptoms in the exam room. In some cases, this prompts further genetic testing and shortens the diagnostic odyssey for pediatric growth disorders – such as Turner syndrome.

Here is a summary of the research findings, delivered as two oral abstracts and a poster session.

ABSTRACT 1: Presented on Saturday, March 23, at 12:30 p.m. CST

Healthy childhood growth cohort provides insight into PAPPA2 and IGF-1 relationship, revealing a new level of complexity to the biology of growth with implications for the study and treatment of severe growth disorders

Program: Growth, puberty, and insulin action and resistance

Session OR07-5: A Cross-Sectional Study of IGF-I Bioavailability through Childhood: Associations with PAPP-A2 and Anthropometric Data

Background: Insulin-like growth factor 1 (IGF-1) is a hormone essential for human growth and is often bound to IGFBP-3, an IGF binding protein. Pregnancy Associated Plasma Protein-A2 (PAPP-A2) cleaves intact IGFBP-3, freeing IGF-1 to support normal growth functions. This is the first study, led by Dr. Andrew Dauber with collaborators from Cincinnati Children’s Hospital Medical Center, to track PAPP-A2 and intact IGFBP-3 concentrations throughout childhood. The research team studied 838 healthy children, ages 3-18, in the Cincinnati Genomic Control Cohort, to better understand patterns of growth and development by examining the relationship between PAPPA2 and IGF-1 bioavailability.

Study results: Free IGF-1 increased with age. PAPP-A2, a positive modulator of IGF-1 bioavailablity, decreased with age, which surprised the researchers, and is not positively associated with absolute levels of free IGF-1. However, higher levels of PAPP-A2 cleave IGFBP-3 resulting in lower levels of intact IGFBP-3, and consequently, increasing the percentage of free to total IGF-1. This demonstrates that PAPP-A2 is a key regulator of IGF-1 bioavailability on a population-wide scale.

Impact: This research may help endocrinologists create unique, targeted treatment for children with PAPPA2 mutations and could help stratify patients with potential risk factors, such as IGF-1 resistance due to increased binding of IGF-1, associated with severe growth and height disorders. See adjoining study below.

Watch: Video interview with Dr. Dauber

ABSTRACT 2: Presented on Saturday, March 23, at 12:45 p.m. CST

Electronic health records can alert physicians to patients who could benefit from genetic testing to identify severe growth disorders

Program: Growth, puberty, and insulin action and resistance

Session OR07-6: Integrating Targeted Bioinformatic Searches of the Electronic Health Records and Genomic Testing Identifies a Molecular Diagnosis in Three Patients with Undiagnosed Short Stature

Background: Despite referrals to pediatric endocrinologists and extensive hormonal analysis, children with short stature due to a genetic cause, may not receive a diagnosis. Electronic health records may help identify patients – based on associated phenotypes and clinical parameters – who could benefit from genetic testing.

Study results: Researchers from three children’s hospitals – Boston Children’s Hospital, Children’s Hospital of Philadelphia and Cincinnati Children’s Hospital Medical Center – gathered data, starting small, with a known variable, or phenotype, associated with severe growth disorders: insulin-like growth factor 1 (IGF-1) resistance. A targeted bioinformatics search of electronic health records led the team to identify 39 eligible patients out of 234 candidates who met the criteria for a possible genetic-linked growth disorder. Participants were included if their height fell below two standard deviations for age and sex and if their IGF-1 levels rose above the 90th percentile. Patients who had a chronic illness, an underlying genetic condition or precocious puberty were excluded. Whole-exome sequencing (WES) was performed on DNA extracted from willing participants, including 10 patients and their immediate family members. The research team identified new genetic causes in three out of 10 patients with severe growth disorders, who were previously missed as having a genetic-linked growth disorder.

Note: Two patients had two novel IGF1R gene variants; a third had a novel CHD2 variant (p. Val540Phe). The two patients with IGF1R variants had a maternally inherited single amino acid deletion (p.Thr28del) and a novel missense variant (p. Val1013Phe).

Impact: Similar EHR algorithms can be replicated to identify pediatric patients at risk for or thought to have other genetic disorders, while expanding genetic research and improving patient care.

Watch: Video interview with Dr. Dauber

POSTER: Presented on Monday, March 25, at 1 p.m. CST

Electronic health record alerts could help detect Turner syndrome, shorten diagnostic odyssey for girls born with a missing or partially-deleted X chromosome

Program: Session P54. Pediatric puberty, ovarian function, transgender medicine and obesity

Poster Board #MON-249: Algorithm-Driven Electronic Health Record Notification Enhances the Detection of Turner Syndrome

Background: Turner syndrome (TS) results from a complete or partial loss of the second X chromosome and affects about one in every 2,500 female births. TS is common in females with unexplained short stature, but the diagnosis is often not made until late childhood (8-9 years), leading to delays in treatment and screening for comorbidities, such as heart conditions, chronic ear infections, vision problems and challenges with non-verbal learning. Using electronic health record (EHR) alarms can help clinicians screen for and diagnose TS patients earlier in life.

Study results: Researchers from Cincinnati Children’s Hospital Medical Center searched EHRs for female patients with idiopathic short stature who met the team’s selection criteria: Their height fell below two standard deviations from the mean for age as well as one standard deviation below the mid-parental height, had a BMI greater than 5 percent and did not have a chronic illness. The search produced 189 patients who met the diagnostic criteria, 72 of whom had not received prior genetic testing. Out of genetic samples available, 37 were compatible for a microarray analysis – which helped the team identify two cases of TS and a third chromosomal abnormality, all of which were missed by routine clinical evaluation.

Impact: DNA samples may not be available for all patients, but clinicians and researchers can identify and integrate tools into EHR’s – creating their own algorithms. An example includes setting up alerts for specific growth parameters, which helps identify and screen patients for TS.

The abstracts Dr. Dauber and his team discuss at ENDO 2019 support ongoing research, including a partnership among four leading children’s hospitals – Children’s National Health System, Boston Children’s Hospital, Children’s Hospital of Philadelphia and Cincinnati Children’s Medical Center – funded by an R01 grant to study how electronic health records can detect and identify novel markers of severe growth disorders.

The researchers hope their findings will also identify and help screen for comorbidities associated with atypical growth patterns, supporting multidisciplinary treatment throughout a child’s life. The study started in August 2018 and includes three sets of unique diagnostic criteria and will analyze WES from dozens of patients over five years.

Read more about Dr. Dauber’s research presented at ENDO 2019 in Endocrine Today and watch his video commentary with Medscape.

Andrew Dauber

Andrew Dauber, M.D., joins Children’s National as Chief of Endocrinology

Andrew Dauber

“Researchers, clinicians and medical trainees are pressed for time,” says Andrew Dauber, M.D. “Merging these three arenas into a joint infrastructure powers institutional collaboration and fuels transformative, cutting-edge care.”

Imagine an endocrinology division staffed with endowed researchers, clinicians and specialists, that serves as an engine of innovation, making it easy for pediatricians to make the right referrals, based on the best research, to endocrinologists who can provide families with cutting-edge care.

Andrew Dauber, M.D., MMSc, the new chief of endocrinology at Children’s National, is turning this dream into a reality. Over the next few years, Dr. Dauber will work with a nationally-ranked endocrinology and diabetes center to build a clinical endocrinology research program, housing specialty clinics for Turner’s syndrome, thyroid care and growth disorders, amongst others.

“Researchers, clinicians and medical trainees are pressed for time,” notes Dr. Dauber. “Merging these three arenas into a joint infrastructure powers institutional collaboration and fuels transformative, cutting-edge care.”

To put his real-life hypothesis of providing an engine for innovation into practice, Dr. Dauber led the interdisciplinary growth center at Cincinnati Children’s Hospital Medical Center and organized a Genomics First for Undiagnosed Diseases Program to study genetic clues for undiagnosed diseases. At Boston Children’s Hospital, he was the assistant medical director for the clinical research unit and held academic appointments with Harvard Medical School.

Dr. Dauber finds it’s critically important to merge clinical practice with research and education. He received his medical degree and a Master’s of Medical Sciences in Clinical Investigation from Harvard Medical School. He has published more than 65 studies examining genetic clues to endocrine disorders, with a focus on short stature and growth disorders.

Dr. Dauber conducted the majority of his research – ranging from studying genetic clues for rare growth disorders and causes of precocious puberty to genes that regulate the bioavailability of IGF1, insulin-like growth factor – while counseling patients, advising students and fellows, managing grants, reviewing studies and speaking at international pediatric endocrinology conferences.

He’s harnessing this data by combining genomic insights with electronic health records and patient registries. While some of this information can be used immediately to identify a high-risk patient, other conditions may take years to understand. Dr. Dauber views this as an investment in the future of pediatric endocrinology.

“I’m excited to join Children’s National and to work in Washington, where we can power our city and the nation with premier partnerships and collaboration,” adds Dr. Dauber. “In addition to using genetic clues to investigate growth disorders, we’re just as enthusiastic about investing in and expanding access to youth-focused diabetes education and care.”

The Division of Diabetes and Endocrinology works with the National Institutes of Health, conducts independent research and received support from the Washington Nationals Dream Foundation for its diabetes program, the largest pediatric diabetes program in the region, which provides community education and counsels 1,800 pediatric patients each year.