CARTPT and obesity due to melanocortin 4 receptor deficiency: Polymorphism studies in the CART gene conducted worldwide have established substantial linkage between a few specific single nucleotide polymorphisms (SNPs) to obesity (del Giudice et al., 2001; Yamada et al., 2002; Guerardel et al., 2005; Rigoli et al., 2010) (Table 3).