[Regular dominance of thumb ankylosis with mental retardation transmitted over 3 generations].

A young girl 12 old, sent to us for obesity, and coxa-epiphysiolysis showed signs of mental retardation and bilateral thumb ankylosis. The fact that the mother was also affected by both of these signs, led to a more detailed genetic research. The latter revealed that not only the daughter, the mother, but also their own mother and may be, the sister, the grand-mother and the great-aunt of the patient had a retardation, a slight dysmorphia, a type A brachydactylia, signs of obesity and an identical ankylosis of both thumbs. This vertical inheritance, affecting apparently females only, but not associated with a high rate of miscarriage, has, it seems, never been reported. The characteristics of this family are being considered and discussed.