Patterns of co-occurring birth defects among infants with hypospadias

Abstract

Introduction: Hypospadias, one of the most common male genital birth defects, occurs in 1 out of every 200 male births in the United States and is increasing in prevalence globally.

Objective: This study aimed to characterize the combinations of birth defects that co-occur with hypospadias more often than expected by chance, while accounting for the complex clustering patterns of congenital defects.

Study design: We analyzed cases with hypospadias and at least one additional co-occurring defect from the Texas Birth Defect Registry born between 1999 and 2014. For each combination, we calculated adjusted observed-to-expected (O/E) ratios, using Co-Occurring Defect Analysis (CODA).

Results: Among 16,442 cases with hypospadias and without known syndromes, 2,084 (12.7%) had at least one additional defect. Many of the birth defect combinations within the highest adjusted O/E ratios included cardiac, musculoskeletal, and additional urogenital defects. For example, a top combination with an adjusted O/E of 139.0 included renal agenesis and dysgenesis, reduction defects of the upper limb, and other anomalies of upper limb (including shoulder girdle). High adjusted O/E ratios were also observed in combinations that included defects outside of the urogenital developmental field. For instance, the combination with the highest O/E ratio included buphthalmos, and congenital cataract and lens anomalies (adjusted O/E ratio: 192.9). Similar results were obtained when we restricted our analyses to cases with second- or third-degree hypospadias.

Discussion: Many combinations in the top results were expected (e.g., multiple urogenital defects); however, some combinations with seemingly unrelated patterns of defects may suggest the presence of some etiologic mechanisms yet to be identified.

Conclusion: In summary, this study described patterns of co-occurring defect combinations with hypospadias that can inform further study and may provide insights for screening and diagnostic practices.

Keywords: Birth defects; Co-occurrence; Epidemiology; Hypospadias; Observed-to-expected ratio.