Novel mutations and spectrum of the disease of NR0B1 (DAX1)-related adrenal insufficiency in Indian children

Background: X-linked adrenal hypoplasia congenita (AHC), due to mutations in the nuclear receptor superfamily 0, group B, member 1 (NROB1)/dosage-sensitive sex reversal, AHC, critical region on the X chromosome, gene 1 (DAX1) gene, usually presents with a salt-wasting adrenal crisis in infancy and hypogonadotropic hypogonadism (HH) in adolescents. Genetic reports in the literature from patients of diverse ethnicity are limited. We describe the atypical clinical characteristics and molecular genetic results in six Indian patients. Methods: Both exons and flanking intronic sequences of the NR0B1 gene were amplified and sequenced in five patients. In the sixth patient, suspected to have a large deletion, multiplex ligation-dependent probe amplification (MLPA) and chromosomal microarray analysis were performed. Results: Sequencing revealed three novel mutations: a nonsense mutation (c.776C >A), a deletion (c.298del), both causing loss of domains which are highly conserved among nuclear receptor families, and a missense mutation (c.1112T>C). In-silico analysis by structure-based protein modeling predicted a de-stabilizing effect of the novel missense mutation. Two previously reported mutations were seen in patients with atypical manifestations such as late-onset adrenal insufficiency and precocious puberty. One patient had a 7.15-Mb contiguous deletion involving the NROB1, Duchenne muscular dystrophy (DMD), glycerol kinase (GK) and melanoma antigen, family B, 16 (MAGEB16) genes. Conclusions: Our report emphasizes the wide clinical spectrum of AHC, including rare manifestations, and enumerates unique mutations in the NR0B1 gene.