Research Article: Extended genotype–phenotype spectrum of 17?-hydroxylase/17,20-lyase deficiency: a nine-case series featuring a novel mutation, suspected TART-like lesions, and multisystem involvement
Abstract:
17?-hydroxylase/17,20-lyase deficiency (17-OHD), a rare congenital adrenal hyperplasia driven by biallelic CYP17A1 variants, shows extensive clinical and molecular heterogeneity; data on rare phenotypes and genotype–phenotype patterns are scarce.
To characterize clinical, hormonal, gonadal pathological, and genetic features of nine Chinese patients with 17-OHD from a single center, expand the population-specific CYP17A1 variant spectrum, explore genotype–subtype trends, and document rare incidental manifestations to inform clinical care and genetic counseling.
A retrospective case series included nine genetically verified patients (seven 46,XY, two 46,XX). SWISS-MODEL homology modeling and American College of Medical Genetics and Genomics (ACMG) criteria were applied to assess the novel variant’s pathogenicity.
The homozygous c.985_987delTACinsAA (p.Y329Kfs * 90) variant predominated in complete-type patients. A novel nonsense variant c.1218G>A, p.W406X, predicted to truncate 103 C-terminal amino acids, was tentatively classified as pathogenic based on PVS1/PM2/PM3/PM4 evidence in one partial-type case. We observed a descriptive trend: biallelic truncating loss-of-function variants correlated with complete 17-OHD, while partial forms carried missense variants with residual enzyme activity. The two 46,XX complete-type patients had bilateral ovarian atrophy and low anti?Müllerian hormone (AMH); two 46,XY patients presented with incidental unilateral sensorineural hearing loss. One 46,XY patient harbored gonadal steroidogenic cell nests resembling testicular adrenal rest tumors (TART), without adrenal-specific immunohistochemistry (IHC) to confirm cellular origin. One proband had two independent monogenic diseases: 17-OHD and left ventricular non-compaction cardiomyopathy, carrying concurrent CYP17A1 and sarcomeric gene (MYBPC3/ACTN2/TTN) variants. All patients had elevated adrenocorticotropic hormone (ACTH), most had low cortisol, and 11-deoxycorticosterone (11-DOC) and corticosterone levels were variably elevated.
This cohort extends the Chinese pathogenic CYP17A1 variant spectrum and reveals tentative genotype–subtype associations plus rare co-occurring phenotypes. Larger multicenter cohorts and functional experiments are needed to validate causal links between atypical manifestations and 17-OHD. Early adrenal steroid profiling and CYP17A1 sequencing are recommended for patients with hypertension, hypokalemia, and disorders of sex development. Serial ovarian reserve testing is required for 46,XX patients, and long-term gonadal imaging follow-up for 46,XY patients with gonadal dysgenesis.
Introduction:
17-OHD is a rare form of congenital adrenal hyperplasia (CAH) caused by mutations in the CYP17A1 gene, with an estimated prevalence of 1–9 per 1,000,000. “Founder effects” have been described in China and Brazil ( 1 , 2 ). The enzyme 17?-hydroxylase/17,20-lyase, encoded by CYP17A1 and expressed in both gonads and adrenal glands, is a key bifunctional enzyme in steroidogenesis: it catalyzes the 17??hydroxylation of pregnenolone and progesterone to yield 17??hydroxylated products, followed by 17,20?bond cleavage to…
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