Novel SCC mutation in a patient of Mexican descent with sex reversal, salt-losing crisis and adrenal failure

Abstract

Congenital adrenal hyperplasia (CAH) is caused by mutations in cytochrome P450 side chain cleavage enzyme (CYP11A1 and old name, SCC). Errors in cholesterol side chain cleavage by the mitochondrial resident CYP11A1 results in an inadequate amount of pregnenolone production. This study was performed to evaluate the cause of salt-losing crisis and possible adrenal failure in a pediatric patient whose mother had a history of two previous stillbirths and loss of another baby within a week of birth. CAH can appear in any population in any region of the world. The study was conducted at Memorial University Medical Center and Mercer University School of Medicine. The patient was admitted to Pediatric Endocrinology Clinic due to salt-losing crisis and possible adrenal failure. The patient had CAH, an autosomal recessive disease, due to a novel mutation in exon 5 of the CYP11A1 gene, which generated a truncated protein of 286 amino acids compared with wild-type protein that has 521 amino acids (W286X). Although unrelated, both parents are carriers. Mitochondrial protein import analysis of the mutant CYP11A1 in steroidogenic MA-10 cells showed that the protein is imported in a similar fashion as observed for the wild-type protein and was cleaved to a shorter fragment. However, mutant’s activity was 10% of that obtained for the wild-type protein in non-steroidogenic COS-1 cells. In a patient of Mexican descent, a homozygous CYP11A1 mutation caused CAH, suggesting that this disease is not geographically restricted even in a homogeneous population.