title: Complex HTR2C linkage disequilibrium and promoter associations with body mass index and serum leptin.
abstract: The occurrence of obesity, eating disorders, and related diseases has increased in many parts of the world. Given that few strong genetic factors have been found, it is clear that these are complex multi-factorial diseases. The serotonin receptor 2C, a member of the 5-HTergic system, has been implicated in the control of phagia and obesity. We report a detailed investigation of linkage disequilibrium (LD) within and between the HTR2C promoter and the flanking sequences around a commonly utilized marker in the second coding exon of HTR2C. We suggest that inconsistent associations between HTR2C and several phenotypes, including obesity, may be due to the LD pattern across the gene in which recombination and gene conversion have been influential. The nucleotide and haplotype distribution is consistent with that of the neutral mutation model. The number of haplotypes suggests demographic influences or over dominant selection that may have a function in HTR2C expression. Using the fine LD pattern, we describe a possible association with promoter haplotypes and diplotypes, including a GT microsatellite, and body mass index (BMI) > or =30 kgm(-2) (P<0.0001). SNP -995G>A heterozygotes, as well as promoter diplotypes, were found to marginally influence higher serum leptin corrected for percentage body fat (P=0.01), which might suggest that these subjects are leptin resistant. Our results complement previous studies of HTR2C in both mice and humans, and suggest the importance of genetic variation and elucidating the fine LD structure in uncovering the genetic factors of obesity.
authors: Center for Genomics and Bioinformatics, Karolinska Institutet, Berzelius Väg 35, 17177 Stockholm, Sweden. shane.mccarthy@cgb.ki.se
authors: Shane
authors: S
authors: McCarthy
authors: Salim
authors: S
authors: Mottagui-Tabar
authors: Yumi
authors: Y
authors: Mizuno
authors: Bengt
authors: B
authors: Sennblad
authors: Johan
authors: J
authors: Hoffstedt
authors: Peter
authors: P
authors: Arner
authors: Claes
authors: C
authors: Wahlestedt
authors: Björn
authors: B
authors: Andersson
mesh_terms: D000328:Adult; D000368:Aged; D015992:Body Mass Index; D006801:Humans; D020738:Leptin / Q000097:blood*; D015810:Linkage Disequilibrium; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000235:genetics; D020641:Polymorphism, Single Nucleotide; D011401:Promoter Regions, Genetic; D044405:Receptor, Serotonin, 5-HT2C / Q000235:genetics*; D054411:Receptors, Leptin
chemical_list: C515448:LEPR protein, human; D020738:Leptin; D044405:Receptor, Serotonin, 5-HT2C; D054411:Receptors, Leptin