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Articles and Updates from Phoenix Children's

April 13, 2021
Medical Genetics: So Much More than DNA Strands
Medical Genetics: So Much More than DNA Strands

This April 13-16, 2021, our Genetics and Metabolism Department and the American College of Medical Genetics and Genomics (ACMG) celebrate the third annual Medical Genetics Awareness Week. This year’s theme, “Celebrating the Contributions of the Entire Medical Genetics Team to Patient Care and Public Health,” highlights the importance of medical genetics professionals on the healthcare team, including medical geneticists, nurse practitioners, physician assistants, laboratory geneticists, genetic counselors, nurses, medical assistants, registered dietitians, and researchers.

When people think of genetics, they often think of that weird spiraling shape with letters attached, or maybe Mendel’s pea pods, galloping zebras, or simply rare exotic conditions that no one has ever heard of. They may say that they have never met anyone with a genetic condition and they certainly don’t have any history of one in their family.

But genetic diseases, though called “rare,” are much more “common” than we think.

“Rare disease” is defined as a condition that affects fewer than 200,000 people. However, there are so many kinds of disorders that when viewed as a group, it is estimated that 1 in 10 Americans have a rare disease. Half of those persons are children.

In fact, the most common health conditions in the general population have a genetic component and the most common neurodevelopmental disorder, autism, with a prevalence of 1 in 54 children, is strongly genetic, with approximately 80% being attributable to genetic factors.

Genetics in autism

In the past, autism has been very difficult to diagnose at the genetic level. However, in the last 10 years, there have been dramatic improvements in genetic technology. These advances allow us to make diagnoses in patients who have no family history and have a normal appearance. Our ability to find the genetic cause of autism has gone from approximately 1% of patients to about 40% over this period. While we often hear about trying to find “the gene for autism,” there are now approximately 3,000 genetic factors that can cause autism. New causes of autism are being found almost every day, with about 300 new genetic factors being discovered per year.

Not only are there advances being made in the field of autism, but there also similar advances in epilepsy, heart diseases, hearing loss and vision disorders.

Gene therapies

Along with the diagnostic improvements, we are now seeing several gene therapies that have been approved by the FDA. Additionally, as we learn more about specific genetic disorders, we have been able to see an increase in the number of drugs available to treat them. Finally, there are now many opportunities for patients and families to participate in research studies that seek to better understand the biological basis of genetic disorders and thereby develop new treatments. Progress in treating genetic disorders is moving forward at a remarkably rapid pace and more new developments are announced almost weekly.

This is truly an exciting time to be in the field of genetics as we are now able to understand our patients’ health conditions at a much deeper level and in many situations, we have the promise of new therapies to offer them soon. We hope you will join us during Medical Genetics Awareness Week as we share our stories and experiences.


Theresa A. Grebe, MD

Theresa A. Grebe, MD
Dr. Terri Grebe is a medical geneticist in the Division of Genetics & Metabolism at Phoenix Children’s Hospital. She is honored to care for children and adults with rare genetic conditions and is passionate about finding answers for families who have been on a diagnostic odyssey with their child. She is the medical director of the Phoenix Children’s PCH 22q Clinic, a member of the Barrow Neurological Institute Cleft & Craniofacial Center team, and participates in several multi-disciplinary clinics. Her research interests include craniofacial and neurogenetic disorders. She is currently the Chair of the American College of Medical Genetics (ACMG) Social, Ethical and Legal Issues Committee. She loves spending time with her family, playing piano, hiking, and reading.


Derek Neilson, MD

Derek Neilson, MD
Dr. Derek Neilson is a board-certified medical geneticist and chief of the Division of Genetics and Metabolism at Phoenix Children’s Hospital.  He is a graduate of Johns Hopkins University in Baltimore, MD and obtained his medical degree at Oregon Health Sciences University in Portland, OR. He trained in pediatrics and genetics at University Hospitals of Cleveland and Rainbow Babies and Children’s Hospital in Cleveland, OH. Dr. Neilson recently joined Phoenix Children’s Hospital after spending 10 years at Cincinnati Children’s Hospital in Cincinnati, OH. In addition to 20+ years of experience in the field of genetics, Dr. Neilson has spearheaded gene discovery efforts, including the discovery that the RANBP2 gene causes the rare disorder acute necrotizing encephalopathy. He founded the current Hypermobility Clinic at Phoenix Children’s and is committed to expanding the availability of genetics to patients throughout the state of Arizona.

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