FTO and obesity due to melanocortin 4 receptor deficiency: Many studies, also in the pediatric population, focus on single nucleotide polymorphisms (SNPs) in genes with a well-described relationship with obesity, such as FTO [5,6,7,8,9,10,11,12,13,14,15], or genes, whose role in obesity is recently gradually being discovered, as the PLAG1 gene [16,17,18].