Nonclassic Congenital Lipoid Adrenal Hyperplasia: A New Disorder of the Steroidogenic Acute Regulatory Protein with Very Late Presentation and Normal Male Genitalia

Abstract

Lipoid congenital adrenal hyperplasia is a severe disorder of adrenal and gonadal steroidogenesis caused by mutations in the steroidogenic acute regulatory protein (StAR). Affected children typically present with life-threatening adrenal insufficiency in early infancy due to a failure of glucocorticoid (cortisol) and mineralocorticoid (aldosterone) biosynthesis, and 46,XY genetic males have complete lack of androgenization and appear phenotypically female due to impaired testicular androgen secretion in utero. The objective of this study was to investigate whether nonclassic forms of this condition exist. Sequence analysis of the gene encoding StAR was undertaken in three children from two families who presented with primary adrenal insufficiency at 2-4 yr of age; the males had normal genital development. Identified mutants were tested in a series of biochemical assays. DNA sequencing identified homozygous StAR mutations Val187Met and Arg188Cys in these two families. Functional studies of StAR activity in cells and in vitro and cholesterol-binding assays showed these mutants retained approximately 20% of wild-type activity. These patients define a new disorder, nonclassic lipoid congenital adrenal hyperplasia, and represent a new cause of nonautoimmune Addison disease (primary adrenal failure).