Causal Association between Arm Fat, Left Leg Fat, and Trunk Fat Masses and Risk of Polycystic Ovarian Syndrome: A Mendelian Randomization Study.

Background: Observational studies have reported that arm fat, left leg fat, and trunk fat masses have different effects on polycystic ovarian syndrome (PCOS). However, the causal relationship between them remains unknown.

Materials and methods: A two-sample Mendelian randomization (MR) study was conducted by utilizing pooled data from the largest Genome-Wide Association Study (GWAS). Random effect inverse variance weighted (IVW) method, weighted median (WM), and MR-Egger regression analysis were the main statistical methods utilized. Finally, a sensitivity assessment was conducted. Cochran's Q test was used to analyze heterogeneity, whereas MR-Egger regression (intercept term) was used to analyze horizontal pleiotropy. The leave-one-out analysis was performed to assess if MR estimates were impacted by a single nucleotide polymorphism (SNP) exhibiting significant horizontal pleiotropy.

Results: This study discovered a significant positive correlation between left leg fat mass, arm fat mass, and trunk fat mass and genetic factors of PCOS (odds ratio (OR): 4.452, confidence interval (CI): 2.740-7.232, p < 0.001, OR: 3.321, CI: 2.248-4.907, p < 0.001, and OR: 2.518, CI: 1.722-3.682, p < 0.001, respectively).

Conclusion: This study indicates that arm fat, left leg fat, and trunk fat masses may be genetically correlated with PCOS.