Ernst Rüdin (1874-1952) and his genealogic-demographic department in Munich (1917-1986): an introduction to their family studies of schizophrenia.

This historical review introduces a series of papers abstracting, reanalyzing and commenting upon family studies of schizophrenia conducted by Ernst Rüdin and his geneologic-demographic department in Munich. These studies, which pioneered many of the methods still critical to psychiatric genetics, are little known in the anglophonic world. Starting with a study of schizophrenia in siblings, members of the Rüdin school expanded to study a wide range of relationships (including grandchildren and nieces/nephews) and disorders (including affective illness, obsessive-compulsive disorder, epilepsy and personality disorders). They examined many methodologic issues in psychiatric genetics including i) ascertainment correction, ii) anticipation, iii) age correction, iv) assortative mating, v) reduced fertility, vi) spectrum disorders, and vii) familial transmission of age at onset. After the rise of Hitler in Germany, Rüdin and his institute became involved in the eugenic policies of the Nazis, raising important questions about possible political abuse of scientific findings in general and those from the field of psychiatric genetics in particular.