Steroid 5-alpha-reductase type 2 (SRD5A2) gene V89L polymorphism and hypospadias risk: A meta-analysis.

BACKGROUND: Hypospadias is a common congenital malformation in males, in which the urethral orifice is found on the ventral side of the penis as a result of incomplete fusion of urethral folds. The etiology of hypospadias is poorly understood, and may be multifactorial, including genetic, endocrine and environmental factors. The steroid 5-alpha-reductase type 2 (SRD5A2) gene, which is mainly expressed in the ventral side of the urethra in the process of male genital development, plays an important role in urethral shaping.

OBJECTIVE: To investigate, with database searches of related published papers, whether SRD5A2 gene V89L polymorphism has an association with hypospadias risk.

METHODS: The following databases were searched for relevant papers, and all published case-control studies of hypospadias were used to perform a meta-analysis: PubMed, Embase, Springer Link, Cochrane Library, China National Knowledge Infrastructure (CNKI), Wanfang, and Weipu. A quality assessment was performed using the Newcastle-Ottawa scale of a case-control study. To assess the strength of the association under various genetic models, odds ratio (OR) and its 95% confidence interval (CI) were calculated using fixed-effect or random-effects model according to the heterogeneity. Overall and stratified subgroup analyses, including ethnicity, source of controls, sample for DNA extraction, and hypospadias classification, were performed. All data were analyzed using Review Manager 5.3.

RESULTS: This analysis included six eligible case-control studies with 1130 cases and 1279 controls. Overall, there was a statistically significant association between hypospadias risk and V89L polymorphism for allele contrast (C vs G: OR 1.91, 95% CI 1.13-3.23), P = 0.02), codominant model (CC vs GG: OR 2.97, 95% CI 1.25-7.04, P = 0.01; GC vs GG: OR 2.36, 95% CI 1.35-4.13, P = 0.003), dominant model (GC + CC vs GG: OR 2.46, 95% CI 1.28-4.72, P = 0.007), and recessive model (CC vs GC + GG: OR 1.91, 95% CI 1.00-3.66, P = 0.05). Moreover, there was also a statistically significant association in some subgroups. The positive results are shown in the Summary Table.

CONCLUSION: This meta-analysis suggested that the V89L polymorphism definitely increases the risk of hypospadias, and the C allele is a genetic risk factor for hypospadias occurrence.