FABP2 and obesity due to melanocortin 4 receptor deficiency: Although numerous investigators have shown that carriers of the Thr54 variant of FABP2 have nearly twice the affinity for long-chain fatty acids compared with those with the Ala54 allele, supporting the potential function of the Ala54Thr polymorphism in the etiology of human obesity, others have not [7,13,14,15,16].