title: IGF-I and IGFBP-3 polymorphisms in relation to circulating levels among African American and Caucasian women.
abstract: Circulating insulin-like growth factor-I (IGF-I) and IGF-binding protein-3 (IGFBP-3) levels have been associated with common diseases. Although family-based studies suggest that genetic variation contributes to circulating IGF-I and IGFBP-3 levels, analyses of associations with multiple IGF-I and IGFBP-3 single nucleotide polymorphisms (SNP) have been limited, especially among African Americans. We evaluated 30 IGF-I and 15 IGFBP-3 SNPs and estimated diplotypes in association with plasma IGF-I and IGFBP-3 among 984 premenopausal African American and Caucasian women. In both races, IGFBP-3 rs2854746 (Ala32Gly) was positively associated with plasma IGFBP-3 (CC versus GG mean difference among Caucasians, 631 ng/mL; 95% confidence interval, 398-864; African Americans, 897 ng/mL; 95% confidence interval, 656-1,138), and IGFBP-3 diplotypes with the rs2854746 GG genotype had lower mean IGFBP-3 levels than reference diplotypes with the CG genotype, whereas IGFBP-3 diplotypes with the CC genotype had higher mean IGFBP-3 levels. IGFBP-3 rs2854744 (-202 A/C) was in strong linkage disequilibrium with rs2854746 in Caucasians only, but was associated with plasma IGFBP-3 in both races. Eight additional IGFBP-3 SNPs were associated with >or=5% differences in mean IGFBP-3 levels, with generally consistent associations between races. Twelve IGF-I SNPs were associated with >or=10% differences in mean IGF-I levels, but associations were generally discordant between races. Diplotype associations with plasma IGF-I did not parallel IGF-I SNP associations. Our study supports that common IGFBP-3 SNPs, especially rs2854746, influence plasma IGFBP-3 levels among African Americans and Caucasians but provides less evidence that IGF-I SNPs affect plasma IGF-I levels.
authors.affiliation: Epidemiology Branch, National Institute of Environmental Health Sciences, P.O. Box 12233, Mail Drop A3-05, Research Triangle Park, NC 27709, USA. daloisio@niehs.nih.gov
authors.forename: Aimee A
authors.initials: AA
authors.lastname: D'Aloisio
authors.forename: Jane C
authors.initials: JC
authors.lastname: Schroeder
authors.forename: Kari E
authors.initials: KE
authors.lastname: North
authors.forename: Charles
authors.initials: C
authors.lastname: Poole
authors.forename: Suzanne L
authors.initials: SL
authors.lastname: West
authors.forename: Gregory S
authors.initials: GS
authors.lastname: Travlos
authors.forename: Donna D
authors.initials: DD
authors.lastname: Baird
mesh_terms: D000328:Adult; D044383:Black People / Q000235:genetics*; D005260:Female; D020022:Genetic Predisposition to Disease; D005838:Genotype; D006801:Humans; D018972:Insulin-Like Growth Factor Binding Protein 3 / Q000097:blood / Q000235:genetics*; D007334:Insulin-Like Growth Factor I / Q000235:genetics* / Q000378:metabolism; D008875:Middle Aged; D016133:Polymerase Chain Reaction; D020641:Polymorphism, Single Nucleotide; D017697:Premenopause / Q000235:genetics; D012044:Regression Analysis; D012307:Risk Factors; D044465:White People / Q000235:genetics*; D001741:Black or African American
chemical_list: D018972:Insulin-Like Growth Factor Binding Protein 3; D007334:Insulin-Like Growth Factor I