What role does FTO play in fertility?

FTO (Fat Mass and Obesity-associated) is a gene strongly linked to obesity and body fat percentage in genome-wide association studies (GWAS). Obesity is a well-established risk factor for fertility issues—it can disrupt hormone balance (e.g., estrogen, testosterone, insulin), impair ovulation, and reduce sperm quality. Some research suggests FTO variants may directly affect reproduction via energy homeostasis and hypothalamic pathways, but the evidence is preliminary and not robust enough for clinical guidance. Direct-to-consumer DNA tests (e.g., MyBody-X) often include FTO SNPs (like rs9939609), but their predictive value for individual fertility is limited. Genetics is only one piece; lifestyle, diet, age, and medical conditions play larger roles. Anyone experiencing fertility concerns should consult a healthcare provider rather than rely solely on genetic testing. Evidence: primarily GWAS for obesity; direct fertility links are mechanistic or weak.