title: A haplotype at the adiponectin locus is associated with obesity and other features of the insulin resistance syndrome.
abstract: Adiponectin is a protein secreted by adipocytes that modulates insulin action. To assess whether variants of this gene contribute to the prevalence of insulin resistance in Caucasians, we genotyped 413 nondiabetic individuals for two single nucleotide polymorphisms (SNPs) at this locus. The two SNPs (45T-->G and 276G-->T) were chosen because of their association with type 2 diabetes in Japanese. Whereas each polymorphism was significantly associated with some correlate of insulin resistance, the haplotype defined by the two together was strongly associated with many components of the insulin resistance syndrome. Homozygotes for the risk haplotype had higher body weight (P = 0.03), waist circumference (P = 0.004), systolic (P = 0.01) and diastolic (P = 0.003) blood pressure, fasting glucose (P = 0.02) and insulin (P = 0.005) levels, homeostasis model assessment (HOMA) for insulin resistance (P = 0.003), and total to HDL cholesterol ratio (P = 0.01). Homozygotes also had significantly lower plasma levels of adiponectin (P = 0.03), independent of sex, age, and body weight. In an independent study group of 614 Caucasians, including 310 with type 2 diabetes, the risk haplotype was confirmed to be associated with increased body weight (P = 0.03) but not with type 2 diabetes per se. We conclude that variability at the adiponectin locus is associated with obesity and other features of the insulin resistance syndrome, but given the nature of the two SNPs, the risk haplotype is most probably a marker in linkage disequilibrium with an as yet unidentified polymorphism that affects plasma adiponectin levels and insulin sensitivity.
authors.affiliation: Research Division, Section on Genetics and Epidemiology, Joslin Diabetes Center, One Joslin Place, Boston, MA 02215, USA.
authors.forename: Claudia
authors.initials: C
authors.lastname: Menzaghi
authors.forename: Tonino
authors.initials: T
authors.lastname: Ercolino
authors.forename: Rosa
authors.initials: R
authors.lastname: Di Paola
authors.forename: Anders H
authors.initials: AH
authors.lastname: Berg
authors.forename: James H
authors.initials: JH
authors.lastname: Warram
authors.forename: Philipp E
authors.initials: PE
authors.lastname: Scherer
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Trischitta
authors.forename: Alessandro
authors.initials: A
authors.lastname: Doria
mesh_terms: D052242:Adiponectin; D000328:Adult; D001794:Blood Pressure; D001900:Boston; D016022:Case-Control Studies; D003094:Collagen / Q000235:genetics; D003924:Diabetes Mellitus, Type 2 / Q000235:genetics; D005260:Female; D014644:Genetic Variation; D005838:Genotype; D006239:Haplotypes; D006579:Heterozygote; D006720:Homozygote; D006801:Humans; D007328:Insulin / Q000097:blood; D007333:Insulin Resistance / Q000502:physiology*; D036341:Intercellular Signaling Peptides and Proteins; D007558:Italy; D007564:Japan; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000235:genetics*; D020641:Polymorphism, Single Nucleotide / Q000235:genetics*; D011506:Proteins / Q000235:genetics*; D012016:Reference Values; D044465:White People / Q000235:genetics
chemical_list: D052242:Adiponectin; D007328:Insulin; D036341:Intercellular Signaling Peptides and Proteins; D011506:Proteins; D003094:Collagen