GPX5 and obesity due to melanocortin 4 receptor deficiency: On the other hand, the lack of association of the other SNPs (TMEM18 rs6548238 C allele, GPX5 rs445870 G allele, ZPR1 rs964184 G allele, and ZBTB16 rs7106340 T allele) with metabolic diseases (obesity or metabolic syndrome) in this work could have been influenced by the sample size.