Primary adrenal insufficiency with normal male external genitalia in a boy with CYP11A1 deficiency

The first and rate-limiting step of steroid hormone biosynthesis is catalysed by mitochondrial cytochrome P450 side-chain cleavage enzyme (CYP11A1). CYP11A1 deficiency is commonly associated with adrenal insufficiency and, in 46 XY individuals, with variable degrees of differences in sex development (DSD). Here, we present a case report of a preadolescent male who presented to our emergency outpatient department in a state of decompensated shock necessitating ionotropic support. Further evaluation confirmed primary adrenal insufficiency. Subsequent clinical exome sequencing uncovered a compound heterozygous mutation in exons one and five of the CYP11A1 gene. This case highlights the varied presentation of CYP11A1 deficiency, showing that it can present as adrenal insufficiency without DSD.