Moreover, because GRIM-19 also functions as a potent regulator of energy metabolism (43) and because sensitivity to metabolic cues in LCs exert a major influence on spermatogenesis and biosynthesis of testosterone (53), failure of testis GRIM-19 expression to decline in a progressive fashion might contribute to the well-known exacerbation of androgen deficiency in aged males (54), some of which occur in the context of obesity (55) or diabetes (56). Here, NDUFA13 is linked to obesity due to melanocortin 4 receptor deficiency.