[Microcephalia vera. Genetic heterogeneity and mental retardation]. / Microfalia vera. Heterogeneidad genética y retraso mental.

Genetic counseling has been carried in 30 families with 51 patients affected of microcephalia. An exogenous cause was determined in 13 cases. In two cases authors do not find a definite aetiology. Microcephalia vera AD can be demonstrated in seven families, and microcephalia vera AR eight. This last form showed always typical phenotype, but the former was present without any peculiar traits. Main observation is that mental retardation is not always conditioned by inheritance form.