[Agenesis and dysgenesis of the os sacrum and the os coccygis: a contribution (author's transl)].

Agenesis and/or dysgenesis of the os sacrum and os coccygis is reported in seven children (4 boys and 3 girls between the ages of 2 and 15). Two of the children had diabetic mothers. The cause may be hereditary or even exogenous (vitamin A deficiency, O (2) deficiency, maternal toxoplasmosis, maternal diabetes). Our cases were compared with 160 cases presented in the literature. The symptomatic therapy, which must be determined on the basis of neurologic, muscular, and urologic findings, is discussed.