Causal relationship between obesity and male infertility:A two-sample Mendelian randomization study
Objective:To clarify the causal relationship between obesity and male infertility through Mendelian randomization(MR)study.Methods:We assessed the causal effect of genetically predicted body mass index(BMI)on the risk of male infertility via a two-sample MR analysis,with the BMIs of 99 998 cases and 12 746 controls as the exposure factor and genetic information on male infertility obtained from a genome-wide association study of 73 479 Europeans.In the univariable MR(UVMR)analysis of the causal relationship,we mainly used inverse variance weighting(IVW),with MR-Egger regression and weighted median filtering as the supplementary methods.Sensitivity analyses including the Cochran's Q test,Egger intercept test,MR-PRESSO,leave-one-out analysis and funnel plot were performed to verify the robustness of the MR results.To evaluate the direct causal effects of BMI on MI risk,mult-ivariable MR(MVMR)was performed.Results:UVMR indicated a causal relationship between genetically predicted BMI and an in-creased risk of male infertility(OR:1.237,95%CI:1.090-1.404,P=0.001).Sensitivity analysis revealed little evidence of bias in the current study(P>0.05).With such risk factors as type 2 diabetes,alcohol consumption and smoking adjusted,MVMR confirmed a direct causal effect of genetically predicted BMI on the risk of male infertility(P<0.05).Conclusion:Genetically pre-dicted BMI may be associated with an increased risk of male infertility.Further studies are expected to explore the underlying mecha-nisms of this association and provide some new strategies for the prevention and treatment of BMI-related male infertility.
obesitybody mass indexcausalitymale infertilityMendelian randomization
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