PRL and obesity due to melanocortin 4 receptor deficiency: Studies of DR2D common variants show unclear results in T2D.67, 75, 76 Recent human studies report that the PRL regulatory element (PREB) is associated with eating disorders,77 and that a variant near the PRL gene (PRL) is associated with obesity in males.78 A PRL gene SNP shows significant associations with lower glycemia during a 2-h oral glucose tolerance tests and a higher level of beta-cell function in a Chinese study.79