Anorectal malformation: familial aspects and associated anomalies.

One hundred and sixty nine patients with anorectal malformation were studied: there were 108 boys, 60 girls, and one case of intersex. Low malformations were more common in both sexes. Over half the subjects had associated malformations. These were more common in the group with high malformations. There was no difference between the sexes in this respect. A family history of similar malformation was found in 15 cases (9%). Where anorectal malformation was the only abnormality in the family an autosomal dominant mode of inheritance was likely, except in one case where there was consanguinity. Where there were associated malformations no single mode of inheritance emerged. Two families with probably hitherto unrecognised recessive syndromes are described. In most cases of anorectal malformation the recurrence risk is low. Multiple associated malformations may indicate recessive inheritance and subsequent pregnancies should be regarded as high risk and full antenatal investigative facilities provided.