What about gr/gr deletions and male infertility? Systematic review and meta-analysis

Introduction: There has been debate about gr/gr deletions and male fertility. In this review, we aimed to quantify the strength of association between gr/gr deletions and male subfertility, and to explore potential sources of heterogeneity.
Material and methods: From each eligible case-control study published in Medline, we abstracted data to calculate odds ratio (OR) and 95% confidence interval (95%CI). We identified potential sources of heterogeneity and performed categorical and meta-regression analyses. We also constructed 2x2 tables for studies providing separate data on cases with azoospermia, oligozoospermia and normozoospermic controls to conduct subgroup meta-analyses.
Results: Pooled estimates from 18 studies indicated that gr/gr deletions were present in 4.94% (95%CI,4.38-5.55) of cases and 3.47% (0-8.92) of controls. The association between gr/gr deletions and infertility was significant (P=0.005). The test for heterogeneity among studies was significant (P=0.029,I²=43%), indicating moderate heterogeneity. The association between gr/gr deletions and subfertility was dependent on the geographic region. Predefined subgroup meta-analysis providing data on cases with azoospermia versus controls showed an increased but statistically non-significant pooled OR of 1.56 (0.80-3.02). No between-study heterogeneity was observed (P=0.63,I²=0%). However, for subgroup meta-analysis providing data on cases with oligozoospermia versus controls with normozoospermia, the pooled OR of 2.19 (1.19 to 4.01) was statistically significant (P=0.011). Again, there was no heterogeneity between studies (P=0.42,I²=0%).
Conclusions: Partial AZFc deletions occur more frequently in subfertile than in control men. When comparing normozoospermic control men to azoospermic or oligozoospermic patients, a significantly higher occurrence of gr/gr deletions is observed only in patients with oligozoospermia.