Abstract
Hypospadias is one of the most common birth defects in China and a key feature of differences in sex development (DSD), yet its genetic etiology remains largely unresolved. Current diagnostic approaches using DSD-targeted gene panels have a low rate of definitive diagnoses (5.5%), highlighting the need for more comprehensive genetic investigation. In this study, we performed next-generation sequencing (NGS) on the largest trio-based cohort of hypospadias to date, comprising 106 pediatric cases and their parents (92 trios). We achieved a definitive genetic diagnosis in 6.6% of patients, identifying pathogenic variants in canonical DSD genes such as AR, NR5A1 and WT1 . By incorporating a broader spectrum of potentially clinically significant variants, we increased the overall genetic identification rate to 33.0% (35/106). Strikingly, trio analysis uncovered a significant burden of de novo loss-of-function (LoF) variants (2.2-fold enrichment, P =0.001), primarily driven by variants in genes associated with ciliopathies (10.35-fold, P =0.016), a previously underappreciated gene class in hypospadias. Furthermore, we identified and functionally validated two high-confidence risk genes, PRKCZ and HRNR , based on recurrent de novo variants. Functional assays confirmed that these variants disrupt key biological mechanisms, including cell proliferation, migration, and androgen signaling. Our large-scale trio approach substantially expands the genetic landscape of hypospadias, demonstrates the critical value of trio-based sequencing for improving diagnostic yield, and decisively implicates ciliary genes in its pathogenesis.