title: Testing for gene-gene interaction controlling total IgE in families from Barbados: evidence of sensitivity regarding linkage heterogeneity among families.
abstract: Genetic heterogeneity has been proposed as a hallmark feature of allergic disease. To test the hypothesis that total IgE levels are jointly influenced by a locus on chromosome 12q21.1-q21.31 and a locus on 17q11.2-q21.2, we conducted multipoint allele-sharing analyses using nonparametric linkage (NPL) methods on Afro-Caribbean families from Barbados to test for evidence of gene-gene interactions. Significant correlations were observed between NPL scores at D12S1052 and both D17S1293 and D17S1299 for a dichotomized phenotype of total IgE. An analysis of family-specific NPL scores revealed that evidence for interaction was being driven largely by one multiplex pedigree (NPL = 12.01, 12.23, and 12.16 at D12S1052, D17S1293, and D17S1299, respectively). Using the programs SIMWALK (v2.0) and GOLD, a different set of haplotypes in this influential family was observed around D12S1052 and the 17q loci compared to the other Barbados pedigrees. Our findings are a classic example of founder effect, provide evidence for sensitivity of this type of linkage analysis to unusual pedigrees, and highlight an element of genetic heterogeneity that has been given little attention in the study of complex traits.
authors.affiliation: Division of Clinical Immunology, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA. kbarnes@jhmi.edu
authors.forename: K C
authors.initials: KC
authors.lastname: Barnes
authors.forename: R A
authors.initials: RA
authors.lastname: Mathias
authors.forename: R
authors.initials: R
authors.lastname: Nickel
authors.forename: L R
authors.initials: LR
authors.lastname: Freidhoff
authors.forename: M L
authors.initials: ML
authors.lastname: Stockton
authors.forename: X
authors.initials: X
authors.lastname: Xue
authors.forename: R P
authors.initials: RP
authors.lastname: Naidu
authors.forename: P N
authors.initials: PN
authors.lastname: Levett
authors.forename: V
authors.initials: V
authors.lastname: Casolaro
authors.forename: T H
authors.initials: TH
authors.lastname: Beaty
mesh_terms: D001249:Asthma / Q000453:epidemiology; D001460:Barbados / Q000453:epidemiology; D002881:Chromosomes, Human, Pair 12 / Q000235:genetics; D002886:Chromosomes, Human, Pair 17 / Q000235:genetics; D005192:Family Health; D005260:Female; D005786:Gene Expression Regulation / Q000235:genetics; D018740:Genetic Heterogeneity; D008040:Genetic Linkage / Q000235:genetics*; D005819:Genetic Markers; D020022:Genetic Predisposition to Disease; D006239:Haplotypes; D006801:Humans; D006967:Hypersensitivity / Q000235:genetics; D007073:Immunoglobulin E / Q000235:genetics* / Q000378:metabolism; D008297:Male; D010375:Pedigree; D010641:Phenotype
chemical_list: D005819:Genetic Markers; D007073:Immunoglobulin E