fff8f195-db1f-480f-b962-fbc895418580
title
Both risk alleles for  FcgammaRIIA  and  FcgammaRIIIA  are susceptibility factors for SLE: a unifying hypothesis.
2ade9b7f-bc6c-48d3-a367-180b9cf7e8a9
abstract
The aim of this study was to analyze in families with SLE for the presence of linkage and the structure and transmission of haplotypes containing alleles for the low-affinity Fcgamma receptors. The Fcgamma receptor polymorphisms  FcgammaRIIA - 131R/H ,  FcgammaRIIIA - 176F/V  and FcgammaRIIIB- NA1/2  and a polymorphism in the FcgammaRIIB gene were genotyped with RFLP, allele-specific PCR or pyrosequencing. Individual SNPs and haplotypes were tested for linkage in multicase families and for association using contingency tables, transmission disequilibrium test and affected family-based control groups in Swedish and Mexican single-case families. No linkage or association could be detected using the FcgammaR polymorphisms in the multicase families. However, an association was found for both  FcgammaRIIA - 131R  and IIIA- 176F  alleles in the single-case families, but not for IIIB or IIB. Allelic association to SLE was found for a haplotype that included both risk alleles, but not in haplotypes where only one or the other was present. We propose that  FcgammaRIIA - 131R  and  FcgammaRIIIA - 176F  are both risk alleles for SLE transmitted primarily, but not exclusively on a single major haplotype that behaves functionally in a situation similar to that of compound heterozygozity.