Impact of linkage disequilibrium on studies of the HLA complex

Regardless of the basis for linkage disequilibrium, it has an important impact upon analyses of HLA antigens in functional and disease association studies. A historical review of the HLA antigens found to be associated with certain diseases illustrates this point. As new loci within the HLA complex were identified, associations with allelic variants of these new loci in linkage disequilibrium were shown to be stronger than previously observed associations. The number of genes mapping to the HLA...

Use of linkage disequilibrium for gene mapping

Two genes may be found in linkage disequilibrium because they are physically close and recombination events do not occur frequently between them, thus linkage disequilibrium analyses have been used in gene mapping studies. Experimental approaches that make use of linkage disequilibrium have been successful in strengthening traditionally performed linkage analyses, particularly those involving genes with few alleles. Certain genes of interest for their role in a particular disease may not be...

Linkage Disequilibrium

Mary Ann Robinson, Laboratory of Immunogenetics, National Institutes of Health, Maryland, USA Linkage disequilibrium is an important concept in genetic studies that aims to identify and or localize genes related to disease susceptibility. The term linkage disequilibrium is commonly used to indicate that two genes are physically linked, however, the strict definition of the term does not specify close genetic linkage. Linkage disequilibrium is defined as the difference between the observed...

Epidemiology and immunogenetics

Since only a handful of studies have been performed, only tentative conclusions can be drawn about the prevalence of the disorder. Disease prevalence had previously been estimated to be 0.2 of the population, with a female male ratio of 9 1. However, in more recent studies in elderly populations, the prevalence of SS was estimated to be approximately 2 in the USA, 3.3 in Scotland and 2.7 in Sweden. Since it has been also estimated that 10-15 of the rheumatoid population suffer from SS, it may...

Conclusions

Human histocompatibility class I molecules consist of a MHC-encoded heavy chain and an invariant 32m. In the HLA gene complex, there are 17-20 class I heavy chain genes including various pseudogenes and gene fragments. Only six genes HLA-A, -B, -C, -E, -F and -G are known to encode 3,m-associated molecules. HLA-A, -B and -C molecules are present on virtually all nucleated cells. HLA-F. and -F transcripts have been detected on almost all cell lines and tissues examined. In contrast, HLA-G...

Supportive transfusion therapy

The majority of patients with autoimmune hemolytic anemia do not require transfusion therapy because the anemia has occurred gradually and there has been physiologic compensation. However, occasionally patients experience acute and or severe anemia and require transfusions for support until other treatment modalities reduce the hemolysis. Transfusion therapy is complicated by the fact that the blood bank may be unable to find any 'compatible' blood. This is because the autoantibody is directed...