title: Fine-mapping the genetic basis of CRP regulation in African Americans: a Bayesian approach.
abstract: Basal levels of C-reactive protein (CRP) have been associated with disease, particularly future cardiovascular events. Twin studies estimate 50% CRP heritability, so the identification of genetic variants influencing CRP expression is important. Existing studies in populations of European ancestry have identified numerous cis-acting variants but leave significant ambiguity over the identity of the key functional polymorphisms. We addressed this issue by typing a dense map of CRP single-nucleotide polymorphisms (SNPs), and quantifying serum CRP in 594 unrelated African Americans. We used Bayesian model choice analysis to select the combination of SNPs best explaining basal CRP and found strong support for triallelic rs3091244 alone, with the T allele acting in an additive manner (Bayes factor > 100 vs. null model), with additional support for a model incorporating both rs3091244 and rs12728740. Admixture analysis suggested SNP rs12728740 segregated with haplotypes predicted to be of recent European origin. Using a cladistic approach we confirmed the importance of rs3091244(T) by demonstrating a significant partition of haplotype effect based on the rs3091244(C/T) mutation (F = 8.91, P = 0.006). We argue that weaker linkage disequilibrium across the African American CRP locus compared with Europeans has allowed us to establish an unambiguous functional role for rs3091244(T), while also recognising the potential for additional functional mutations present in the European genome.
authors.affiliation: Section of Molecular Genetics and Rheumatology, Faculty of Medicine, Imperial College, Du Cane Road, London W12 0NN, UK.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Rhodes
authors.forename: David L
authors.initials: DL
authors.lastname: Morris
authors.forename: Lakshman
authors.initials: L
authors.lastname: Subrahmanyan
authors.forename: Cristin
authors.initials: C
authors.lastname: Aubin
authors.forename: Carlos F Mendes
authors.initials: CF
authors.lastname: de Leon
authors.forename: Jeremiah F
authors.initials: JF
authors.lastname: Kelly
authors.forename: Dennis A
authors.initials: DA
authors.lastname: Evans
authors.forename: John C
authors.initials: JC
authors.lastname: Whittaker
authors.forename: Jorge R
authors.initials: JR
authors.lastname: Oksenberg
authors.forename: Philip L
authors.initials: PL
authors.lastname: De Jager
authors.forename: Tim J
authors.initials: TJ
authors.lastname: Vyse
mesh_terms: D001741:Black or African American / Q000235:genetics*; D000368:Aged; D000369:Aged, 80 and over; D001483:Base Sequence; D001499:Bayes Theorem; D002097:C-Reactive Protein / Q000235:genetics*; D002318:Cardiovascular Diseases / Q000235:genetics; D002874:Chromosome Mapping; D015331:Cohort Studies; D005260:Female; D005786:Gene Expression Regulation / Q000235:genetics*; D005838:Genotype; D006801:Humans; D015810:Linkage Disequilibrium; D008297:Male; D008969:Molecular Sequence Data; D010802:Phylogeny; D020641:Polymorphism, Single Nucleotide
chemical_list: D002097:C-Reactive Protein