Sporadic mutations in melanocortin receptor 3 in morbid obese individuals.
Several mutations in the melanocortin receptor 4 gene have been identified in humans and account for 3-6% of morbid obesity. In contrast, strong evidence of a causative role for melanocortin receptor 3 (MC3R) mutations are still lacking. In MC3R knockout mice, high feed efficiency rather than hyperphagia seems to contribute to increased fat mass. On the basis of this evidence, the objective of the present study was to investigate the presence of MC3R mutations in a group of 290 obese subjects (mean BMI 44.2+/-5.9 kg/m2). As a control, a group of 215 normal-weight subjects (mean BMI 22.4+/-2.7 kg/m2) was also screened. Three novel mutations in the MC3R gene (A293T, I335S and X361S) were identified among the obese patients. The mutations segregated with obesity in the members of the families studied. In vitro expression studies of each mutation demonstrated a loss of function of the I335S-mutated receptor. These findings suggest that, in humans, MC3R mutations may be a cause of a dominantly inherited form of obesity. However, this association as well as the specific phenotypic characteristics resulting from these mutations need to be further evaluated in larger series of obese subjects.
Mencarelli
Monica
M
Molecular Biology Laboratory, Istituto Auxologico Italiano, Piancavallo, Italy.
Walker
Gillian E
GE
Maestrini
Sabrina
S
Alberti
Luisella
L
Verti
Barbara
B
Brunani
Amelia
A
Petroni
Maria Letizia
ML
Tagliaferri
Mariantonella
M
Liuzzi
Antonio
A
Di Blasio
Anna Maria
AM
D000328:Adult; D000368:Aged; D000818:Animals; D019556:COS Cells; D016022:Case-Control Studies; D002522:Chlorocebus aethiops; D000242:Cyclic AMP / Q000378:metabolism; D004252:DNA Mutational Analysis; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009154:Mutation; D009767:Obesity, Morbid / Q000235:genetics*; D010375:Pedigree; D044104:Receptor, Melanocortin, Type 3 / Q000235:genetics* / Q000378:metabolism
D044104:Receptor, Melanocortin, Type 3; D000242:Cyclic AMP