An unusual case of congenital adrenal hyperplasia (CAH) with two enzyme defects

Abstract

Classical CAH is caused by a genetic defect (or defects) resulting in a deficiency or absence of the steroid hydroxylases catalysing the introduction of hydroxyl groups at any of the 21, 3 and 11 positions. The daily output by normal infants of pregnanetriol (PT), androsterone (A) and aetiocholanolone ( β A), are each in the low microgram range. A 21 -hydroxylase-deficient boy had a daily excretion of over 20 mg PT, 4 mg A and 2 mg β A. However the rare case presented shows only the increase in PT (1.5 mg/day), A and β A being present in trace amounts only. This indicates that in addition to the 21-hydroxylase block which causes a build-up of Cortisol precursors, excreted largely as PT, there is also a deficiency of the desmolase which would convert some of these precursors to C 19 metabolites, these being excreted largely as conjugates of A and β A.