Dr. Gillis is board certified in pediatric gastroenterology. She also specializes in pediatric hepatology and pediatric gastroenterology. Dr. Gillis completed her internship in general surgery at Massachusetts General Hospital in 1996, her medical education at Pennsylvania State University College of Medicine in 1996, her residency in pediatrics at Pennsylvania State University College of Medicine in 2000, and her fellowship in pediatrics/medical genetics & genomics at Children's Hospital of Philadelphia in 2004.