The results of subgroup study on the patients’ races showed that longer AR-CAG repeat length was associated with male infertility in Asian, Caucasian, and population of mixed races (SMD = 0.25, 95% CI: 0.08–0.43, P <0.01; SMD = 0.13, 95% CI: 0.02–0.25, P <0.05; SMD = 0.39, 95% CI: 0.15–0.63, P <0.01) (Figure 2). This evidence concerns the gene AR and male infertility.