The parent-reported degree of hyperphagia in PHP1A (mean total HQ score 24.2 ± 8.4) was less severe than that seen in patients with Prader–Willi syndrome (30.47 ± 4.52), but closer to other causes of syndromic obesity such as Bardet–Biedl syndrome (27.6 ± 9.0) and BDNF haploinsufficiency (26.37 ± 7.32) [11,23,24]. This evidence concerns the gene BDNF and obesity disorder.