1. IgA deficiency and the MHC: assessment of relative risk and microheterogeneity within the HLA A1 B8, DR3 (8.1) haplotype.
- Author
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Mohammadi J, Ramanujam R, Jarefors S, Rezaei N, Aghamohammadi A, Gregersen PK, and Hammarström L
- Subjects
- Computer Simulation, DNA Mutational Analysis, Gene Frequency, Genetic Heterogeneity, Genetics, Population, HLA-A1 Antigen genetics, HLA-B8 Antigen genetics, HLA-DR3 Antigen genetics, Humans, IgA Deficiency epidemiology, Prevalence, Risk, Sample Size, Sweden, Haplotypes, IgA Deficiency genetics, IgA Deficiency immunology, Immunoglobulin A metabolism, White People
- Abstract
Introduction: Selective IgA deficiency (IgAD; serum IgA concentration of <0.07 g/l) is the most common primary immunodeficiency in Caucasians with an estimated prevalence of 1/600. The frequency of the extended major histocompatibility complex haplotype HLA A1, B8, DR3, DQ2 (the "8.1" haplotype) is increased among patients with IgAD., Materials and Methods: We carried out a direct measurement of the relative risk of homozygosity of the 8.1 haplotype for IgA deficiency in a population-based sample of 117 B8, DR3 homozygous individuals., Results and Discussion: IgA deficiency was found to be present in 2 of 117 (1.7%) of these subjects, a figure that is concordant with estimates of relative risk from large case-control studies in the Swedish population. These data are consistent with a multiplicative model for the 8.1 haplotype contribution to IgA deficiency and contrasts with prior studies, suggesting a much higher risk for 8.1 homozygosity. Using a dense single nucleotide polymorphism marker analysis of the MHC region in HLA B8, DR3, DQ2 homozygous individuals, we did not observe consistent differences between cases (n = 26) and controls (n = 24). Overall, our results do not support the hypothesis that IgA deficiency is associated with a distinct subgroup of 8.1 related haplotypes, but rather indicate that risk is conferred by the common 8.1 haplotype acting in multiplicative manner.
- Published
- 2010
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