In female Ay mice withgenetically induced obesity, unlike males, FGF21 did not affectbody weight, blood insulin levels, or POMC expression in thehypothalamus, but increased food intake and liver weight andmodified the expression of metabolic genes in the liver and inwhite adipose tissue (Makarova et al., 2020). The gene discussed is FGF21; the disease is obesity due to melanocortin 4 receptor deficiency.