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Epigenetics & Chromatin Clinic

The mission of the McKusick-Nathans Epigenetics and Chromatin Clinic is:

  • To diagnose and provide optimal care for patients with either classical epigenetic disorders or mutations of the epigenetic machinery
  • To learn from our patients some fundamental truths about epigenetics with the hope that this additional knowledge will lead to therapeutic development for our patients in the future
  • To educate health providers and patients about epigenetics and the disorders of the epigenetic machinery
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Conditions We Treat

We welcome confirmed diagnoses as well as rule-in/out for genetic aneurysm pre-disposing conditions, such as:

  • Alpha thal and MR (ATRX)
  • Angelman syndrome (UBE3A)
  • Autosomal Dominant MR (MBD5)
  • Beckwith-Wiedemann Syndrome (IGF2)
  • Borjeson-Forssman-Lehmann syndrome (PHF6)
  • Brachydactyly MR syndrome (HDAC4)
  • CHARGE syndrome (CHD7)
  • Coffin-Lowry syndrome (RSK2)
  • Coffin-Siris syndrome (ARID1B)
  • ICF syndrome 1 (DNMT3B)
  • Kabuki syndrome (MLL2, KDM6A)
  • Kleefstra syndrome (EHMT1)
  • Opitz-Kaveggia syndrome (MED12)
  • Prader-Willi syndrome (SNRPN, NDN)
  • Rett syndrome (MECP2)
  • Rubinstein-Taybi syndrome (CBP, EP300)
  • Russell-silver syndrome (IGF2)
  • Schinzel-Giedion (SETBP1)
  • Sotos/Weaver syndrome (NSD1)
  • Syndromic micro-ophthalmia (BCOR)
  • Transient Neonatal Diabetes(ZFP57/PLAGL1)
  • Turner type, XLMR (HUWE1)
  • Weaver syndrome 2 (EZH2)
  • Williams syndrome (WINAC) 
  • XLMR Claes-Jensen type (KDM5C)
  • XLMR93 (BRWD3)
  • X lined mental retardation (PHF8)

Epigenetics and Chromatin Clinic Team

Hans Tomas Bjornsson, MD, PhD

Director of the Epigenetics and Chromatin Clinic

Dr. Bjornsson has a long standing interest in epigenetic diseases. Dr. Bjornsson did his graduate work under the supervision of Andrew P. Feinberg, the director of the Center of Epigenetics at Johns Hopkins University. After this, Dr. Bjornsson joined the combined program in pediatrics and human genetics at Johns Hopkins, where he acted as Chief Resident of Genetics from 2011 to 2012. In 2012, Dr. Bjornsson become Assistant Professor of Pediatrics and Genetics to the McKusick-Nathans Institute of Genetic Medicine. He has received multiple awards while at Johns Hopkins both for research and for clinical care including the Margaret Ellen Nielsen Fellow Award, Francis F. Schwentker Award and Frank L. Coulson, Jr. Award for Clinical Excellence. Dr. Bjornsson is also the Assistant Residency Program Director for clinical genetics.

Jill A. Fahrner, MD, PhD

Clinical Geneticist

Dr. Fahrner has a long-standing interest in epigenetics. She did her thesis research with Dr. Stephen B. Baylin in the Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins. Her graduate work culminated in multiple publications in the field of cancer epigenetics and in a thesis entitled Aberrant epigenetic silencing of tumor suppressor genes in human cancer: the roles of DNA hypermethylation and the histone code. She completed medical school at the University of North Carolina and Pediatrics residency at Duke University Medical Center. She joined the McKusick-Nathans Institute of Genetic Medicine as a Genetic Medicine resident in 2009 and completed her training in 2012. She stayed on as chief resident from 2012 to 2013 and then joined the faculty as an Assistant Professor in the Department of Pediatrics within the McKusick-Nathans Institute of Genetic Medicine in 2013. She has received the Margaret Ellen Nielsen Fellowship Award and the Alice and YT Chen Travel Award while at Johns Hopkins, and she is currently an Assistant Residency Program Director for the Johns Hopkins Genetic Medicine Residency Program.

Carolyn D. Applegate, MGC, CGC

Senior Genetic Counselor

Applegate MGC, CGC is a senior counselor within the McKusick-Nathans Institute of Genetic Medicine. She has extensive experiences in counseling complex patients with genetic disorders and has specific interest in epigenetic disorders.


Felicia Easley

Sr. Medical Office Coordinator

Felicia is the Clinic Coordinator for our Skeletal Dysplasia Clinic in the Institute of Genetic Medicine at the Johns Hopkins University School of Medicine. She handles patient scheduling and coordinates their visit to all other necessary appointments