IgA nephropathy in a patient with 17α-hydroxylase/17,20-lyase deficiency caused by the CYP17A1 p. Y329fs mutation: a case report and review

17α-Hydroxylase/17,20-lyase deficiency (17-OHD) is a rare form of congenital adrenal hyperplasia caused by mutations in the CYP17A1 gene. The p. Y329fs mutation is the most prevalent variant of CYP17A1 in the Chinese population. IgA nephropathy (IgAN) is the most common primary glomerulonephritis globally, with a notably higher prevalence observed in East Asian populations. The co-occurrence of these two conditions has not been previously documented. A 13.5-year-old phenotypically female patient presented with hypertension and proteinuria. Steroid profiling revealed markedly elevated levels of deoxycorticosterone (2351 pg/mL), corticosterone (110,993 pg/mL), and 18-hydroxycorticosterone (2287 pg/mL), alongside suppressed aldosterone levels (0.82 pg/mL)—a pattern indicative of 17-OHD. Genetic testing, performed via Sanger sequencing and whole-exome sequencing identified a heterozygous p. Y329fs mutation (c.985_987delinsAA) in the CYP17A1 gene; her mother was found to carry a heterozygous p.S106P variant. Renal biopsy confirmed the diagnosis of IgAN. Light microscopy showed mild mesangial proliferative changes without significant glomerular basement membrane thickening or crescent formation. Immunofluorescence revealed granular, comma‑like IgA deposition predominantly in the mesangial areas. Tubular epithelial cells exhibited vacuolar and granular degeneration. No obvious vascular lesions were observed in the small arterial walls Treatment with hydrocortisone replacement therapy successfully normalized the patient's blood pressure, and the electrolyte levels remained stable and within normal limits during the follow-up period. To our knowledge, this report presents the first documented case of biopsy-proven IgAN occurring concurrently with a heterozygous case of 17-OHD in a patient harboring the p. Y329fs hotspot mutation. These findings underscore the importance of regular urinalysis and blood pressure monitoring in patients with 17-OHD, particularly among individuals of East Asian descent, to facilitate the early identification of potentially treatable glomerular diseases.