BDNF and obesity due to melanocortin 4 receptor deficiency: Moreover, an obesity-risk-allele score, comprising variants in or near the FTO, MC4R, TMEM18, GNPDA2, KCTD15, NEGR1, BDNF and ETV5 (SFRS10) loci has been tested for an association with birth weight in 7,146 individuals [17] and a modest association with BMI at birth was observed.