Sir Cyril Astley Clarke, physician and geneticist, is best known for his studies of the Rh factor and the introduction of Rhogam, a means of preventing Rhesus hemolytic disease, a condition that had caused thousands of infant deaths.

Clarke was born in Leicester, England. During World War I, Clarke, the son of a physician, was sent to the safety of the English countryside. While away from Leicester, Clarke became fascinated by butterflies and began collecting and breeding them. This hobby eventually led to his work in genetics. Clarke attended Caius College, Cambridge University from 1926 to 1929. After earning his MD at Guy's Hospital Medical School, London, in 1932, he remained at Guy's as a resident physician until 1936. From 1936 to 1939 Clarke was involved in life-insurance work in London. During World War II, Clarke served in the Royal Navy. He was listed on the medical registrar of the Queen Elizabeth Hospital, Birmingham...