A study of the association of HLA DR, DQ, and complement C4 alleles with systemic lupus erythematosus in Iceland

To access publisher full text version of this article. Please click on the hyperlink in Additional Links fieldOBJECTIVE: To perform an exploratory analysis of the relative contribution of single MHC genes to the pathogenesis of systemic lupus erythematosus (SLE) in a homogenous white population. METHODS: MHC class II alleles and C4 allotypes were determined in 64 SLE patients and in ethnically matched controls. HLA-DR and DQ typing was performed by polymerase chain reaction amplification with sequence specific primers. C4 allotypes were determined by agarose gel electrophoresis. RESULTS: The frequency of C4A*Q0 was significantly higher in patients than in controls (46.9% v 25.3%, p = 0.002). HLA-DRB1, DQA1, and DQB1 alleles in the whole group of SLE patients were not significantly different from those of controls. On the other hand increase in DRB1*03 was observed in the group of patients with C4A*Q0, as compared with patients with other C4A allotypes (p = 0.047). There was no significant correlation between severe and mild disease, as judged by the SLEDAI, and HLADR, DQ alleles and comparing the patients with C4A*Q0 with those with other C4A allotypes there was no significant difference regarding clinical manifestations. CONCLUSION: The results are consistent with the argument that C4A deficiency contributes independently to susceptibility and the pathogenesis of SLE. C4A*Q0 in SLE patients in Iceland shows weaker linkage disequilibrium with DR3 genes than reported in most other white populations and emphasises the role of ethnicity

Contrasting genetic structuring in the closely related basidiomycetes Trichaptum abietinum and Trichaptum fuscoviolaceum (Hymenochaetales)

Trichaptum abietinum and Trichaptum fuscoviolaceum (Hymenochaetales, Basidiomycota) are closely related saprotrophic fungi, widely distributed on coniferous wood in temperate regions worldwide. Three intersterility groups have previously been detected in T. abietinum, while no prezygotic barriers have been proven within T. fuscoviolaceum. The aim of this study was to reveal the phylogeography and genetic relationship between these two closely related species and to explore whether the previously observed intersterility groups in T. abietinum are reflected in the genetic data. We assembled worldwide fruit body collections of both species (N = 314) and generated DNA sequences from three nuclear (ITS2, LSU, IGS) and one mitochondrial rDNA region (mtLSU). The two species are genetically well separated in all analyses. In correspondence with observations from earlier mating studies, our results revealed that T. fuscoviolaceum is genetically more uniform than T. abietinum. Multiple genetic sub-groups exist in T. abietinum that may correspond to the previously observed intersterility groups. However, there is low consistency across the investigated loci in delimiting the different sub-groups, except for a consistent North American group. As for many other widespread fungi, a complex phylogeographic pattern is found in T. abietinum which may have been formed by geographic, as well as multiple genetic intersterility barriers