Lipoid congenital adrenal hyperplasia due to steroid acute regulatory protein (STAR) variants in Three Chinese patients

Abstract

Congenital adrenal hyperplasia (CAH) encompasses a group of autosomal recessive diseases characterized by enzymatic defects in steroid synthesis. Lipoid congenital adrenal hyperplasia (LCAH) is the most severe form of CAH, insofar as the initial step of steroid synthesis is impaired. Variants in the steroid acute regulatory (STAR) gene are responsible for LCAH. To describe the clinical and genetic characteristics of three Chinese patients with LCAH. We analyzed the history, clinical manifestations, physical examination, laboratory data, and computed tomography findings of three girls with LCAH. The STAR gene of the probands and their parents were sequenced using genomic DNA. The wild-type and mutant STAR cDNAs were inserted into the pcDNA3.1(+) plasmid vector and transiently transfected into COS7 cells. The enzymatic activities of the wild-type and mutant STAR were evaluated by the enzyme-dependent conversion efficiency of cholesterol to pregnenolone. We identified the molecular genetic abnormalities in three patients with LCAH. All three patients had a female phenotype: karyotype of patients 1 and 2 was 46, XY and patient 3 was 46, XX. DNA sequencing revealed compound heterozygous variants in STAR for three probands. Two variants, c.659A > G/p.His220Arg and exon 2–3 deletion, were novel. In vitro functional studies uncovered that the His220Arg variant retained 19.2 % of enzymatic activity compared to that of the wild type.