In humans, congenital mutation of the ob gene is rare, although patients with early-onset extreme obesity have been reported; cousins from a consanguineous Pakistani family, involved the absence of leptin due to homozygous frame shift mutation in leptin gene [36], and a boy of Turkish consanguinity, whose parents were of normal weight was reported to be obese due to homozygous transversion (c.298G -> T), resulting in mutated leptin that failed to bind ObR [37]. This evidence concerns the gene LEPR and obesity due to melanocortin 4 receptor deficiency.