Significant association between a silent polymorphism in the neuromedin B gene and body weight in German children and adolescents

Neuromedin B has been shown to exert an inhibiting effect on food consumpti on in rats. The corresponding gene NMB maps to chromosome 15q22.3-q23, a re gion expected to contain a gene for the Bardet-Biedl syndrome type 4 (BBS4) . Based on its map position and the putative function of the encoded peptid e, NMB can be considered as a candidate gene both for BBS4 and the developm ent of human obesity. To examine its involvement in these phenotypes, we de termined the genomic structure of human NMB, and performed a mutation scree n in its coding region. In genomic DNA of six BBS4 patients and in a large population sample, two sequence variants were detected: a g.253C-->A transv ersion creating a P73T substitution and a g.401G-->A silent mutation changi ng the stop codon TGA into stop codon TAA. A case-control study with 92 ext remely obese patients and 94 underweight students revealed a significant as sociation between the g.401G-->A polymorphism and body weight (adjusted p = 0.03), which was confirmed in a validation sample consisting of 95 extreme ly obese patients, and 95 normal weight and 48 underweight individuals (Man n-Whitney p = 0.02). These results suggest a contribution of NMB or a gene in its close vicinity to genetic weight control in humans.