Penrose, Lionel Sharples (1898–1972)

English physician and geneticist who carried out pioneering work on mental retardation and Down's syndrome. He was the first to demonstrate the significance of the mother's age.

Penrose was born in London and educated at Cambridge. He was director of psychiatric research for Ontario, Canada, 1939–45. In 1945 he became professor of eugenics at London University.

While working as research medical officer at the Royal Eastern Counties Institution, Colchester, 1930–39, Penrose produced an influential survey of patients and their families (A Clinical and Genetic Study of 1,280 Cases of Mental Defect 1938), showing that there were many different types and causes of mental defect and that normality and subnormality were on a continuum.

Early in his career, Penrose advanced the study of schizophrenia and developed a test for its diagnosis. His subsequent work concentrated on the causes of Down's syndrome.