Prevalence of mutations and functional analyses of melanocortin 4 receptor variants identified among 750 men with juvenile-onset obesity.
Mutations in the gene encoding the melanocortin 4 receptor (MC4R) are associated with the most common monogenic form of obesity. We examined 750 Danish men with juvenile-onset obesity (body mass index 33.3 +/- 2.4 kg/m(2)) and 706 control subjects (body mass index 21.4 +/- 2.1 kg/m(2)) for mutations in MC4R. A total of 14 different mutations were identified of which two, Ala219Val and Leu325Phe, were novel variants. The variant receptor, Leu325Phe, was unable to bind [Nle4,d-Phe7]-alphaMSH, whereas the Ala219Val variant showed a significantly impaired melanotan II induction of cAMP, compared with the wild-type receptor. The remaining 11 mutations have previously been reported, but selected MC4R variants were further characterized in vitro in the present study. A previously identified nonsense mutation, Tyr35stop, had a relatively high allele frequency (0.6%), suggesting a possible founder effect in the Danish population. This study shows a carrier frequency of 2.5% of pathogenic mutations in the MC4R gene in a population-based study of obese men. Thus, variation in this gene is the most common known specific genetic cause of obesity among Scandinavian men.
Steno Diabetes Center and Hagedorn Research Institute, Niels Steensens Vej 6, NSK 1.14, 2820 Gentofte, Denmark. LieL@Steno.dk
Lesli H
LH
Larsen
Søren M
SM
Echwald
Thorkild I A
TI
Sørensen
Teis
T
Andersen
Birgitte S
BS
Wulff
Oluf
O
Pedersen
D000328:Adult; D015331:Cohort Studies; D006801:Humans; D008297:Male; D009154:Mutation; D009765:Obesity / Q000235:genetics*; D044105:Receptor, Melanocortin, Type 4 / Q000235:genetics* / Q000502:physiology
D044105:Receptor, Melanocortin, Type 4