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

March 25, 2019

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 bioavailability, 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.

Thirteen questions for a pediatric endocrinologist

December 27, 2018

Andrew Dauber, M.D., hosts an AMA chat with Reddit’s science community and offers feedback about height, growth disorders and pediatric endocrinology.

Andrew Dauber, M.D., MMSc., the division chief of endocrinology at Children’s National, spoke about epigenetics – how genes are expressed – and about all things related to pediatric endocrinology in a recent Ask Me Anything (AMA) chat with Reddit’s science community.

We’ve selected highlights from several questions Dr. Dauber received. You can view the full AMA discussion on Reddit.

Q1: What will the future of type 1 diabetes treatment look like?

As a pediatric endocrinologist, Dr. Dauber sees a lot of patients with type 1 diabetes. He predicts technology will pave the way for advancements with continuous glucose monitoring and encourage a ‘real-time’ interaction between patients and providers:

“I anticipate that within a few years, everyone will have access to continuous glucose monitoring technology and that these will be seamlessly connected to insulin pumps or artificial pancreas technologies,” types Dr. Dauber in response to the first AMA question. “I also think there will be more virtual interaction between medical providers and patients with doctors and nurses reviewing blood sugar data in the cloud.”

Q2: What height range is considered normal for a growing child? What is the difference between short stature and a height problem?

The Centers for Disease Control and Prevention has a growth chart, which shows ‘normal’ ranges, based on statistical definitions of height in the general population.

“The truth is that I know plenty of people who have heights below the ‘normal’ population, and they don’t think they have a problem at all,” says Dr. Dauber. “From a genetics point of view, the question can be reframed: When do we call a genetic variant a ‘mutation’ versus a rare variant in the population? For example: If there is a genetic change that 1 in a 1,000 people have that causes you to be 2 inches shorter – is that a problem? Is that a disease?”

“From a clinical perspective, I tend to have a discussion with my patients and their families and ask them how their stature is affecting their lives and whether changing that would really make a meaningful difference,” adds Dr. Dauber. “I believe that this is a very personal decision but people need to be realistic about expected outcomes.”

Q3: What are your favorite case studies about atypical growth or height patterns?

Dr. Dauber references two case studies about growth and puberty:

The growth case study refers to the PAPPA2 gene, which was particularly meaningful for Dr. Dauber since he got to know the family and was able to provide answers to a previously undiagnosed medical mystery about short stature. This research is also opening future studies and analysis about the regulation of IGF-1 bioavailability.

The puberty case study looks at the opposite end of growth and development: precocious puberty. In this case an inherited MKRN3 gene mutation resulted in new insight about the regulation of pubertal timing: Deficiency of MKRN3 caused central precocious puberty in humans. Girls who had inherited the mutated genes from their father (an imprint gene) started to develop breasts before age 6. The results were published in The New England Journal of Medicine.

Q4: What are the differences with consistent and inconsistent growth disorders? Could one arm or leg experience accelerated or stunted growth?

“Most genetic disorders that affect growth will have a uniform effect throughout the body as they are likely to affect all aspects of the skeleton,” says Dr. Dauber. “That being said, there are some notable exceptions such as Russell-Silver syndrome which presents with body asymmetry. There are also somatic mutations (mutations which are just present in some cells in the body) that can lead to segmental areas of overgrowth leading to asymmetry.”

Q5: Can you predict height and growth by looking at genetic factors? What are your thoughts about polygenic risk scores?

“Polygenic risk scores will probably play more of a role in the future to help determine risk of a certain disease,” says Dr. Dauber. “Right now, for most conditions, the risk score does not explain a substantial enough fraction of the variation to help with prediction.”

Dr. Dauber discusses how this works for height, a highly hereditable trait, in The Journal for Clinical Endocrinology and Metabolism. In the review, Dr. Dauber and the study co-authors note that individuals with extreme heights are more likely to have abnormal stature as a result of a severe mutation that causes a growth disorder. For these individuals, whole exome sequencing may reveal gene mutations.

However, the study authors note that for now, the role of these technologies in individuals with extreme stature but without any syndromic features has not been rigorously and systematically explored. (Dr. Dauber and a team of endocrinologists from leading children’s hospitals are currently using electronic health records to study and track these types of genetic clues over time.)

Q6: The general public is excited about genetics and ongoing research, especially with consumer applications – such as genetic tests, including 23andMe. What misconceptions about genetics do people have? What ethical concerns do geneticists share right now?

“Many people think that genetics is completely deterministic,” says Dr. Dauber. “In reality, most genetic variants influence a person’s predisposition toward a trait or disease but don’t actually determine the outcome. Also, the genetic sequence itself is just the first step. Epigenetics, gene regulation, and gene-environment interactions are all important and we are just scratching the surface of understanding these areas.”

“I think that people engaged in genetics research are very interested in the ethical questions,” adds Dr. Dauber. “The problem is that technology is advancing at such a rapid pace, that often consumers are using technologies in ways that we haven’t yet had time to figure out the ethics for. The medical community is often playing catch up.”

Q7: Aside from using gene modifications to cure diseases, where or when should we draw the line in terms of enhancement?

“I think genetic modification for enhancement is a very dangerous slippery slope that we should avoid,” says Dr. Dauber. “We really don’t know the full effect of many genes and by enhancing them, we could be causing lots of problems that we can’t anticipate. There is a reason that evolution is a slow process that happens over millions of years. I think we need to start with the most devastating diseases and try to cure those first.”

Q8: Would it be ethical to use CRISPR on the genes for short stature to produce tall offspring if the risks are sufficiently small? This would be similar to what Dr. He did, but without the ethical violations.

“This is a fascinating question and it will become more of an issue over time,” says Dr. Dauber. “Where do we draw the line between fixing, preventing disease and enhancing physical function? Personally, I think using genome editing to promote height is a terrible idea. Our current perception that taller height is more desirable is a social construct and varies by culture. This idea also changes over time.”

Q9: Overall, how does this fit into meeting unmet medical needs?

“I would be very wary about trying to design our children’s physical features,” Dr. Dauber notes. “We need to figure out as a society what diseases are sufficiently problematic that we feel comfortable trying to eliminate them via genome editing.”

Q10: How many genes control acromegaly? Is it possible (in theory) to Top of Formselect them just to gain the positive effects of gigantism without the health risks?

Dr. Dauber explains that acromegaly, a condition often referred to as gigantism, is caused by a growth hormone-producing tumor. There are a few genes known to cause these tumors, including the AIP, and there was recently a genetic cause of X-linked gigantism, which was published in The New England Journal of Medicine.

“This basic idea is a good one,” notes Dr. Dauber. “We can find genes that when mutated can cause tall stature – and then try to manipulate those pathways. A great example is the NPR2 gene, which when mutated can cause short or tall stature. This pathway is being targeted for therapeutics related to achondroplasia.”

The National Institutes of Health (NIH) refers to achondroplasia as ‘short-limbed dwarfism,’ which results in an average-sized trunk with short limbs, especially arms and legs, due to a lack of cartilage turning into bone. The average height of an adult male with achondroplasia is 4 feet, 4 inches, while the average height of adult females with achondroplasia is less than 4 feet, 1 inch. In this case, manipulating growth pathways may help alleviate health problems associated with achondroplasia: lack of mobility or range of motion, an enlarged head, apnea, ear infections and spinal stenosis, or a compression or pinching of the spinal cord.

Q11: Give us a history lesson. Why are there variations of height within populations, such as Asia and Latin America?

“The average height in a population is due to the influence of literally thousands of common genetic variants,” says Dr. Dauber. “These population differences have evolved over thousands of years due to a combination of migration and selection. There is a well-known difference in the genetic makeup of various populations which likely underlies the differences across the globe. There are even differences within Europe.”

Q12: Are there examples of pseudoscience or theories about growth, such as recommendations to eat a certain food instead of taking growth hormones to correct for a growth disorder, which runs contrary to scientific evidence, that drive you crazy?

“I don’t really get bothered by crazy theories, but it is upsetting when patients and their families get swindled into spending their money on therapies that aren’t truly effective,” says Dr. Dauber. “People ask me all the time if a certain food or exercise can make their child taller. The bottom line is that in a well-nourished (and healthy) child, there is no magical food that is going to make them tall.”

Q13: According to almost every theory of how life evolved on Earth, from religion to evolution, we all have one common ancestor. In theory doesn’t that make us all cousins?

“Yes, just very distant ones,” says Dr. Dauber. “People always point out the vast number of differences between races but in fact we are all more than 99.9 percent identical on a genetic level.”

Stay on top of the latest pediatric endocrinology news by following @EndoDocDauber and @ChildrensHealth on Twitter: #GrowUpStronger.

PAPPA2: A genetic mystery

October 31, 2018

Test tube that says IGF-1 test

What would happen if you suddenly stopped growing at age 12 or 13?

Solving genetic growth mysteries and scheduling regular appointments with pediatric endocrinologists is atypical for most parents and pediatricians.

However, for children with growth disorders – a classification that typically describes children below the third or above the 97th percentile of growth charts for their age – receiving a diagnosis is half the battle to reaching average height. Understanding and creating treatment for a growth disorder, which could stem from an underlying medical illness, a genetic mutation or a problem with endocrine function, such as the production or action of growth hormone, is often the next step.

For Andrew Dauber, M.D., MMSc., the chief of endocrinology at Children’s National Health System, a third step is to use these clues to create larger datasets and blueprints to identify risk factors for rare growth disorders. By understanding genetic markers of growth disorders, endocrinologists can identify solutions and create plans for multidisciplinary care to help children reach developmental milestones and receive coordinated care throughout their lifespan.

A case study that Dauber and his research team continue to explore is how to correct for mutations in the PAPPA2 gene, which regulates human growth by releasing a key growth factor called insulin-like growth factor 1 (IGF-1). Dauber and his colleagues recently described a mutation in PAPPA2, observed in two families with multiple children affected with significant short stature. He found that this mutation decreased the bioavailability of IGF-1, stunting the growth and development of the children who carry this mutation.

While the PAPPA2 mutation is rare, endocrinologists, like Dauber, who understand its function and dysregulation can create solutions to support IGF-1 bioavailability, thereby supporting healthy growth and development in children.

Understanding barriers to IGF-1 function can also help researchers gain insight into the relationship between PAPPA2, levels of circulating insulin in the body, which could cause insulin resistance, and other growth hormones. For now, Dauber and his research team are exploring how to use PAPPA2 to increase IGF-1 in circulation among people with height disorders in the hopes of improving their growth.

“The population of children who have PAPPA2 mutations is small and we’re finding out that two children could respond to the same treatment in different ways,” says Dauber. “One medication could work modestly in one child and support short growth spurts, such as growing by 5 or 6 cm a year. It could also create undesirable side effects, such as headaches and migraines in another, and render it ineffective. However, the clues we walk away with enable us to test new solutions, and confirm or dissolve our hunches, about what may be preventing the bioactive release of essential growth hormones.”

To generate controls for healthy patterns of growth and development, Dauber and his research team are analyzing the relationship between PAPPA2, STC2 and IGFBP-3 concentrations among 838 relatively healthy pediatric participants, ages 3-18, with traditional growth patterns.

They are studying PAPPA2, STC2 and intact IGFBP-3 concentrations throughout childhood and the researchers are already surprised to find PAPPA2, a positive modulator of growth and IGF- bioavailability, decreased with age, while STC2, a negative modulator and traditional growth inhibitor, increased with age.

“As pediatric endocrinology researchers and clinicians, we’re looking at the pathology of traditional growth patterns and growth disorders with an open mind,” says Dr. Dauber. “These data sets are invaluable as they confirm or challenge our theories, which enable us to create and test new forms of personalized treatments. We’ll continue to share this knowledge, which informs other researchers and accelerates the field of pediatric endocrinology.”

This research was presented at the annual meeting of the European Society of Pediatric Endocrinology in Athens on Sept. 28, 2018.

Dauber and his research team will present their findings at endocrinology conferences and grand rounds throughout 2018 and 2019.

To view Dr. Dauber’s most recent research and pediatric endocrinology reviews, visit PubMed.

Growth disorder study starts by analyzing DNA

October 31, 2018

The National Institutes of Health has awarded Andrew Dauber, M.D., MMSc, the chief of endocrinology at Children’s National Health System, a five-year grant that will allow four pediatric health systems to compile and study clinical and genetic markers of severe pediatric growth disorders.

The study will use the electronic health records of large health systems combined with DNA samples from dozens of children, with the goal of enabling endocrinologists to detect children with previously undiagnosed severe genetic growth disorders.

“If you’re a pediatrician treating an 8-year-old patient who has stopped growing, the first thing you’ll want to do is determine the underlying cause, which could be due to many factors including a genetic mutation,” says Dr. Dauber. “There are many reasons why children grow poorly and it is often very difficult to figure out what is causing the problem. However, the various causes may be treated quite differently and may alert us to other medical issues that we need to watch out for. We need to be able to identify clues from the patient’s clinical presentation that may point us to the right diagnosis.”

Dr. Dauber and endocrinology researchers from Children’s National Health System, Cincinnati Children’s Hospital Medical Center, Boston Children’s Hospital and The Children’s Hospital of Philadelphia will use electronic health records to identify children who likely have rare genetic growth disorders. They will then use cutting-edge DNA sequencing technologies, whole exome sequences, to identify novel genetic causes of severe growth disorders. Patients with growth hormone resistance, resistance to insulin-like growth factor 1 (IGF-I) and severe short stature inherited from a single parent will be recruited for the initial phases of the study.

“It’s rare to find patients meeting criteria for each of these subgroups, which is why it’s critical to work collaboratively across institutions,” says Dr. Dauber. “This type of genetic sorting and sharing brings us closer to identifying new markers for severe or treatment-resistant growth disorders, which will help alert pediatricians and parents to potential risks earlier on in a child’s life.”

In addition to assessing genetic markers for short stature, the endocrinologists will conduct pilot studies of targeted interventions, such as IGF-I therapy in patients with mutations in the growth hormone pathway, based on these genetic underpinnings.

“Ideally, by identifying markers of severe growth disorders first, we’ll be able to provide targeted treatments and therapies later on to help patients throughout their lifespan,” adds Dr. Dauber.

Typical treatments for atypical growth patterns include growth hormone or less commonly insulin-like growth factor, or IGF-1, for short stature and hormone-inhibiting treatments for precocious puberty.

The multicenter clinical trial is funded by the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), under grant Ro1HD093622, and runs through June 30, 2023.