What role does MC4R play in fertility?

MC4R (melanocortin-4 receptor) is primarily known for its role in energy homeostasis and appetite regulation. Mutations in MC4R are the most common monogenic cause of early-onset obesity. Since severe obesity can impair fertility in both women and men (e.g., through hormonal disturbances such as insulin resistance, altered leptin levels, and disrupted gonadotropin secretion), there is an indirect link between MC4R and fertility. Direct effects of the receptor on reproduction are also discussed: MC4R is expressed in the hypothalamus and may modulate GnRH release. Animal studies suggest involvement in female reproduction, but human data are limited. The evidence is therefore moderate: the connection is plausible but not sufficiently established to use MC4R variants as independent fertility markers. Clinically, obesity-related effects are more relevant. Genetic testing for MC4R polymorphisms such as rs17782313 (associated with obesity) does not provide direct information about fertility. For those trying to conceive, lifestyle, weight, and hormonal factors should be prioritized.