[Genetic counseling and the caudal regression syndrome].

It has been published about 500 cases of caudal regression (sacral agenesis) of which 12 are undoubtly familial. In most of the non familial cases an aetiology is not demonstrable except the cases related to maternal diabetes and/or insulin treatment. A genetic control of the caudal regression is implicit in the familial transmission. Three sporadic new cases are reported and, at the occasion of the genetic counselling we analyse the 8 well reported genealogies. Among 133 subjects, 72 show some evidences of caudal regression. This is compatible with a pattern of autosomic dominant transmission. The analogy with the caudal regression anomaly of the mouse, in which the role of genes located closely to the histocompatibility system is demonstrated, evokes such a relation in the human with the major histocompatibility system. If true, this may be used as a genetic marker, especially for early antenatal diagnosis.