The familial occurrence of congenital adrenal hyperplasia long has been known; and although the genetics of this condition have not been analyzed definitively, it has been postulated that the condition is determined by a recessive gene.1 Under these circumstances, the occurrence of congenital adrenal hyperplasia in first cousins in the absence of consanguinity in the parents would be extremely unusual and should occur less frequently than once per 3,000,000 births. Money, in 1952, cited by Childs,2 has reported the occurrence of the condition in first cousins. Until the present time no additional reports of the occurrence of congenital adrenal hyperplasia in first cousins have been made. It is the purpose of this report to describe this disease in first cousins of two unrelated families. Each patient was studied extensively and in each an unequivocal diagnosis was made.
Plasma 17-hydroxycorticosteroid (17-OHCS) concentrations were determined by the method of