Developmental Convergence of Syndromic Cryptorchidism: A Genotype–Phenotype Analysis Across Genetically Heterogeneous Developmental Disorders

Background/Objectives: Cryptorchidism occurs in numerous genetic developmental disorders, yet these associations are generally considered syndrome by syndrome, and the biological basis for their recurrence across molecularly heterogeneous conditions remains poorly understood. We aimed to characterize the clinical and molecular findings and develop a hypothesis-generating framework of developmental convergence. Methods: We retrospectively evaluated children with documented rare developmental disorders who underwent surgical treatment for cryptorchidism at a tertiary pediatric urology center between 2015 and 2025. Clinical, operative, and molecular data were analyzed at patient and testis levels, and disorder-specific associations with cryptorchidism were evaluated through targeted literature review. Results: Among 94 children screened, 26 met the inclusion criteria, contributing 41 undescended testes. Cryptorchidism was bilateral in 57.7% of patients, 53.7% of testes were nonpalpable, and 51.2% were located at a high inguinal or intra-abdominal level. Despite substantial molecular heterogeneity, the underlying abnormalities could be organized into five interconnected developmental domains involving gene expression regulation, signal sensing and integration, neural information transmission, neuromuscular execution and fetal mechanobiology, and mesenchymal and structural implementation. Conclusions: We propose that genetically distinct developmental disorders may perturb different levels of the biological system required for testicular descent while converging on shared downstream morphogenetic processes. This developmental convergence model is hypothesis-generating and provides a testable framework linking human genetics, developmental biology, and pediatric urology.