The Genetics of Phenylpyruvic Oligophrenia

Although considerable attention has been devoted during the past years to the problems of the influence of heredity on mental deficiency, no final conclusions have yet been reached. It appears well established at the present time, first, that in a large percentage of cases, variously estimated at from 40 to 80%, mental deficiency is significantly determined by genetic mechanisms, and second, that recessive genes seem to play a considerable role in such mechanisms (Lokay, 1929; Brugger, 1930a; Smith, 1930; Luxemburg, 1931; Juda, 1934; Kreyenberg, 1935).