Twelve Brazilian families with X-linked Congenital Adrenal Hypoplasia: new rearrangements and new variants in the NR0B1 gene

OBJECTIVE: To characterize the molecular spectrum of NR0B1 variants associated with X-linked congenital adrenal hypoplasia (X-hypoAC) in a multicenter Brazilian cohort and to highlight the clinical implications of early molecular diagnosis. METHODS: The authors investigated 12 unrelated families referred to pediatric endocrinology centers across Brazil with a clinical diagnosis of early-onset adrenal insufficiency. Clinical data, biochemical profiles, and follow-up information were collected. Genetic testing of the NR0B1 gene was performed by Sanger sequencing to detect single-nucleotide and small insertion/deletion variants, complemented by MLPA to identify large deletions or rearrangements. Variants were classified according to the American College of Medical Genetics and Genomics (ACMG) guidelines. RESULTS: All probands presented with adrenal insufficiency within the first months or years of life, often requiring hospitalization and lifelong glucocorticoid and mineralocorticoid replacement. Molecular analysis revealed a heterogeneous spectrum of NR0B1 pathogenic variants, including frameshift, nonsense, and missense variants, as well as large and small deletions, which together accounted for nearly half of the cases. Clinical follow-up confirmed that, in addition to adrenal insufficiency, affected individuals frequently developed hypogonadotropic hypogonadism during puberty, with infertility documented in adulthood. The identification of novel variants contributes to expanding the mutational spectrum of NR0B1and reinforces the genotype-phenotype variability in X-hypoAC. CONCLUSIONS: This study represents one of the largest Brazilian series of X-hypoAC. The present findings broaden the molecular landscape of NR0B1 variants and underscore the relevance of early genetic testing to differentiate X-hypoAC from congenital adrenal hyperplasia, optimize long-term clinical management, and provide accurate genetic counseling for affected families.