Rheumatoid Arthritis and HLA Genotyping

Rheumatoid arthritis (RA) is a complex autoimmune disease with a strong genetic contribution to its pathogenesis. Genetic factors account for the majority of population susceptibility to this disease. Human leukocyte antigen (HLA) is a cluster of genes located on the short arm of chromosome 6 between bands 6p21.31 and 6p32, spans a DNA segment of about 4000 kbp, and represents about 1% of the whole genome in Human. The HLA complex contains over 200 genes, more than 40 of which encode leukocyte antigens. It's polygenic. There are several genes for each class of molecule, and polymorphic, large number of alleles exists in the population for each of the genes. The HLA molecules have been suspected to play a role in the pathogenesis of autoimmune diseases such as RA, Insulin Dependent Diabetes Mellitus, and Multiple Sclerosis.