This child was clinically diagnosed with MKKS because of the symptoms displayed at the first assessment but no mutation was found in MKKS gene, so we decided to review our data in search of mutations in other BBS genes, since it is well-known that many patients diagnosed with MKKS during neonatal period or early childhood may turn out to be a case of BBS years later, developing retinal dystrophy and obesity [67, 68]. The gene discussed is MKKS; the disease is obesity due to melanocortin 4 receptor deficiency.