On aetiological factors in hypospadias.

An analysis of genetic and non-genetic factors which might be of importance for the aetiology of hypospadias was performed in a clinical and in a registered material comprising altogether 893 hypospadiacs. Of 213 index patients in the clinical material, the probable aetiology was known in 11: in 3 patients chromosomal aberrations, in 2 well-defined syndromes with a known genetic background, in one maternal diabetes, in 2 maternal rubella, and 2 of the hypospadiacs were born after the mothers' use of anticonvulsant drugs and one after the mother's use of thalidomide. Other hypospadiacs were identified in 28 of the families of the remaining 202 index patients. As regards inheritance, 10 cases of hypospadias associated with clinodactyly were found in one family and this suggests an autosomal dominant gene as the cause of hypospadias. In the great majority (174/213) of index patients neither genetic nor non-genetic factors could be demonstrated but a significant cyclic trend for the month of birth and the month of the last menstrual period was found.