Gastroenterology, Hepatology and Nutrition | Fellowships | Meet the Fellows

1st Year Fellows

Daniel Lapp, MD, PhD, attended Eastern Menninite University in Harrisonburg, VA for his undergraduate studies, earning a BS in Biochemistry. He completed his medical training as well as a PhD in neuroscience as part Penn State College of Medicine's MD/PhD program in Hershey, PA. His pediatric residency training was in Charleston, SC at the Medical University of South Carolina. As a Gastroenterology Fellow at Washington University in St. Louis he is interested in transplant hepatology and endoscopy. He enjoys participating in half-marathons and exploring St Louis with his wife and 2 children.
Chaowapong (Chao) Jarasvaraparn, MD, graduated from Medical School at Ramathibodi Hospital, Mahidol University in Bangkok, Thailand. He completed his Pediatric Residency training at the University of South Alabama in Mobile, Alabama. Currently, he is a fellow with the Pediatric Gastroenterology Fellowship Program at Washington University School of Medicine in St. Louis, Missouri. His research interests include sleep disturbance associated with Inflammatory Bowel Disease, a pH probe-impedance study in GERD, cow milk protein intolerance. His hobbies include going to the gym, tennis, hanging out with friends, traveling and good coffee.

2nd Year Fellows


Mallory Cohen, M.D. obtained her undergraduate degree in neurobiology, physiology and behavior at University of California, Davis and medical degree at St George's University. She completed her Pediatric Residency training at University of Nevada in Las Vegas. Her interests in the field are Inflammatory Bowel Disease and hepatology. She enjoys hockey games, spending time with family, visiting the beach and traveling.

Nadia Naz, M.D. completed medical education from Dow University of Health Sciences, Karachi, Pakistan and Pediatric Residency training from SUNY Downstate Medical Center, Brooklyn, NY. She then decided to join a Pediatric Gastroenterology Fellowship Program at Washington University School of Medicine in St. Louis. She is interested in doing an additional fellowship year in Advanced Transplant Hepatology. Nadia enjoys participating in fundraising for charities, cooking, sightseeing and traveling, in her spare time.

3rd Year Fellows


Brendan Harris, M.D. obtained his undergraduate degree in Investigative and Medical Sciences at Saint Louis University and medical degree at University of Missouri-Columbia. He completed his Pediatric Residency training at Riley Hospital for Children in Indianapolis and returned to St. Louis to complete his training in Pediatric Gastroenterology and Nutrition at St. Louis Children’s Hospital. His interests in the field are Functional Gastrointestinal Disorders, Inflammatory Bowel Disease and procedures. He enjoys sports, exercising, grilling/cooking, and spending time with his wife and family. 

Ryan Pitman, M.D. obtained his undergraduate degree from Concordia University in Seward, NE and Masters degree at the University of Illinois at Chicago. He completed medical education at the Chicago Medical School at Rosalind Franklin University of Medicine and Science and Pediatric Residency at St. Louis Children's Hospital. He decided to stay at Washington University in St. Louis in the Pediatric Gastroenterology Fellowship program. He is interested in Cystic Fibrosis and Nutrition. He enjoys running, cooking, hiking and spending time with his wife and young son.
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