title: Heritability and genetics of serum dickkopf 1 levels in African ancestry families.
abstract: The aim of the study was to determine the heritability of serum dickkopf-1 (DKK1) and its association with DKK1 polymorphisms in African ancestry subjects. Serum DKK1 was measured in 422 Afro-Caribbean men and women aged 18+ from 7 large, multi-generational families (mean family size: 60; 3,215 relative pairs). Twenty-four common single nucleotide polymorphisms (SNPs) were genotyped within an 80 kilobase-pair region encompassing the DKK1 gene. Heritability was estimated and SNPs were tested for association with serum DKK1 using variance components analysis. DKK1 mRNA expression was tested in peripheral blood of 16 individuals from each of the rs7069912 genotypes. Mean serum DKK1 was 1724.1 pg/mL and was significantly lower in women than men (P = 0.043). Residual genetic heritability of serum DKK1 was 0.4460 (P < 0.0001). Six SNPs reached nominal significance with DKK1, with rs7069912 being significant after adjustment for multiple comparisons. Two of these six SNPs represented independent association signals (rs7069912 and rs16928725), which accounted for 4.6% of the phenotypic variation in DKK1. Additionally, carriers of the rs7069912 variant had significantly greater DKK1 expression than non-carriers (P = 0.036). Serum DKK1 levels are highly heritable in the African ancestry families. Two SNPs within the DKK1 region accounted for nearly 5% of the variation in serum DKK1.
authors.affiliation: Department of Epidemiology, Graduate School of Public Health, University of Pittsburgh, 130 DeSoto St, A543 Crabtree Hall, Pittsburgh, PA, 15261, USA, kuipers@pitt.edu.
authors.forename: Allison L
authors.initials: AL
authors.lastname: Kuipers
authors.forename: Shibing
authors.initials: S
authors.lastname: Yu
authors.forename: Candace M
authors.initials: CM
authors.lastname: Kammerer
authors.forename: Cara S
authors.initials: CS
authors.lastname: Nestlerode
authors.forename: Clareann H
authors.initials: CH
authors.lastname: Bunker
authors.forename: Alan L
authors.initials: AL
authors.lastname: Patrick
authors.forename: Victor W
authors.initials: VW
authors.lastname: Wheeler
authors.forename: Yingze
authors.initials: Y
authors.lastname: Zhang
authors.forename: Joseph M
authors.initials: JM
authors.lastname: Zmuda
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D044383:Black People / Q000235:genetics; D005260:Female; D020022:Genetic Predisposition to Disease; D005838:Genotype; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000097:blood* / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D020641:Polymorphism, Single Nucleotide / Q000235:genetics*
chemical_list: C501126:DKK1 protein, human; D036341:Intercellular Signaling Peptides and Proteins