7438 DAX1/NR0B1 Related Adrenal Hypoplasia Congenita Without Hypogonadotropic Hypogonadism

Abstract Disclosure: R.L. Figueiredo: None. J.B. Drummond: None. A. Meireles: None. J.L. Machado: None. G. Vidigal: None. B.S. Rocha: None. Background: X-linked congenital adrenal hypoplasia (AHC) is a rare disease caused by genetic mutations in DXA1/NRB01 gene, which encodes a nuclear hormone receptor expressed in the adrenal cortex, gonads, hypothalamus and anterior pituitary gland, occurring in less than 1:12,500 live births (1,2). AHC is characterized by primary adrenal insufficiency (PAI) associated with hypogonadotropic hypogonadism (HH) and impaired spermatogenesis (oligospermia or azoospermia). Although DAX1/NR0B1 mutations can manifest with different phenotypes, HH is mostly present, which makes this present case a diagnostic challenge. Clinical case: A 23-year-old man presented with typical symptoms of adrenal insufficiency at the age of 7 (abdominal pain, dehydration, nausea, vomiting and cutaneous hyperpigmentation). Initial testing was consistent with primary adrenal failure: elevated ACTH levels (1250pg/mL, RR<46pg/mL) and very low serum cortisol (0.8mcg/dL, RR 3-20mcg/dL). Etiological investigation excluded autoimmune etiology (negative anti-adrenal and anti-21-hydroxylase antibodies) as well as adrenoleukodystrophy (normal very long chain fatty acid levels). Physical exam revealed normal virilization, testicular volume and penile length. The patient reported normal libido and sexual function. Hormonal evaluation showed normal total testosterone (424 and 713ng/dL, RR 165 to 753ng/dL) as well as calculated free testosterone (7.2 and 11.4ng/mL, RR>3.8ng/mL) levels. Abdominal CT showed signs of bilateral adrenal hypoplasia. We then proceeded to genetic testing that revealed a pathological variant c.625C>T:p (Gln 209*) in hemizygosity in exon 1 of the DAX 1/NR0B1 gene. This is a nonsense mutation that introduces a premature stop codon. This variant is not present on the global and Brazilian genetic databases (gnomAD and ABraOM) and has not been previously described in the literature. The patient is currently being treated for adrenal insufficiency with the lowest tolerated dose of prednisone (7.5mg/day) and fludrocortisone 0.1mg/day. Conclusion: Etiological investigation of patients with PAI is essential to understand the evolution of the disease, monitoring extra-adrenal manifestations and the possibility of genetic counseling for the family. An intact hypothalamic-pituitary gonadal axis should not preclude genetic evaluation for a DAX/NR0B1 mutation in patients with PAI and suspected AHC. Further studies will clarify if this specific mutation carries a genotype-phenotype correlation in patients with AHC without HH. References: 1) García-Medina J. S. et al. A novel pathogenic variant in NR0B1 gene associated with congenital adrenal hypoplasia. Andes pediatr. 20222) Iughetti L. et al. Isolated hypoaldosteronism as first sign of X-linked adrenal hypoplasia congenita caused by a novel mutation in NR0B1/DAX-1 gene: a case report. BMC Medical Genetics. 2019 Presentation: 6/2/2024