PCSK1 and obesity due to melanocortin 4 receptor deficiency: Since prohormone convertase 1 is involved in proinsulin conversion and thereby in insulin maturation as well as in body weight regulation, the present study examined the association of the putatively obesity-related SNPs rs6232 and rs6235 in PCSK1 with the prediabetic traits insulin resistance, β-cell dysfunction, and glucose intolerance.