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Gastroenterologists specialize in treatment of various digestive disorders, liver diseases, and surveillance of the entire gastrointestinal tract. McHenry Medical Group’s three GI specialists accept new patients by referral only. 

William Griffiths, M.D., Ph.D., joined McHenry Medical Group in November of 1980 and is a shareholder and officer in the corporation. Dr. Griffiths became board certified in internal medicine in 1976 and completed his fellowship in gastroenterology in 1978 at the University of Oklahoma. Dr. Griffiths received his Ph.D. in 1976 at the University of Oklahoma with a thesis in “Growth Hormone and Sleep Interactions.” He has taught at Yosemite Community College District over the years.

Richard Plotzker, M.D., joined McHenry Medical Group on July 1, 1982. Dr. Plotzker completed his internal medicine internship and residency at the Rush-Presbyterian-St. Luke’s Medical Center in Chicago, Illinois, in 1980 and completed a gastroenterology fellowship at University of California San Francisco Medical Center in 1982. Born in Chicago, Dr. Plotzker and his wife have lived in Modesto since 1982. Dr. Plotzker is currently open to new patients.

Michael Ringer, M.D., joined McHenry Medical Group in May of 1988. Dr. Ringer completed his internal medicine internship and residency at Creighton University of Affiliated Hospitals in Nebraska in 1984 and completed a gastroenterology fellowship at Harbor-UCLA Medical Center in Torrance, California, in 1986. He received his board certification in gastroenterology in November of 1987. Dr. Ringer, his wife, and four children live in Modesto. Dr. Ringer is currently open to new patients.