About Mark

Mark H. Johnston, M.D., currently works in a private gastroenterology practice in Lancaster, Pennsylvania. He is a retired U.S. Navy Captain and former head of Gastroenterology at the National Naval Medical Center in Bethesda, Maryland, where he served as a gastroenterology consultant to the White House, U.S. Congress, and the Supreme Court during the 1990's. 
 

Dr. Johnston, who earned a Doctor of Medicine degree from Hahnemann University in Philadelphia, holds two U.S. patents in GI research and is the inventor of endoscopic cryospray ablation using liquid nitrogen.

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He has received numerous military, academic, research, and humanitarian awards for his service and participated in multiple short-term medical mission trips to Albania, Kenya, and China.
 

Mark and his wife, Lavonne, have been married for more than forty years, and their three adult children have all chosen careers in medicine and surgery.

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Together, Mark and Lavonne have hiked in dozens of national parks in the U.S. and Canada. In 2022, Mark made a solo trek on the Camino Frances, a 540 mile spiritual pilgrimage from Saint-Jean-Pied-de-Port in southern France to Santiago, Spain.

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17 Cairns is his first book.