Causal Effects of Gut Microbiota on Abnormal Spermatozoa: A Two-Sample Mendelian Randomization Study

Several clinical studies have reported the link between gut microbiota and abnormal spermatozoa. However, whether gut microbiota plays a causal role in abnormal spermatozoa remains unclear. The present study used genome-wide association study (GWAS) summary data to perform two-sample Mendelian randomization to investigate causal associations between the gut microbiota and abnormal spermatozoa. SNPs that showed significant correlations with genus at genome-wide significance thresholds (P < 1× 10-5, F >10) were identified as potential instrumental variables. The inverse variance weighted method was used as the primary analysis. The results showed a causal effect of gut microbiota components on abnormal spermatozoa. Erysipelotrichaceae, Streptococcaceae, Coprococcus1, RuminococcaceaeUCG009, Streptococcus, and Erysipelotrichales were positively correlated with the risk of abnormal spermatozoa. And Porphyromonadaceae and Prevotella9 were negatively correlated with abnormal spermatozoa. Our analyses prove a potential causal relationship between several gut microbiota taxa and abnormal spermatozoa. This study supports that there are beneficial or detrimental causal effects of gut microbiota components on abnormal spermatozoa. However, more studies are necessary to reveal the impact of gut microbiota on abnormal spermatozoa.