Triplet repeat polymorphism in the transmembrane region of the MICA gene: A strong association of six GCT repetitions with Behçet disease

摘要: A member of a novel family the human major histocompatibility complex (MHC) class I genes termed MIC (MHC chain-related genes), MICA, has been recently identified near HLA-B gene on short arm chromosome 6. The predicted amino acid sequence MICA chain suggests that it folds similarly to typical chains and may have capacity bind peptides or other ligands. Therefore, is specialized function in antigen presentation T cell recognition. During nucleotide analyses genomic clone, we found triplet repeat microsatellite polymorphism (GCT/AGC)n transmembrane (TM) region gene. In 68 HLA homozygous B lines, 5 distinct alleles this were detected. One them contained an additional one base insertion created frameshift mutation resulting premature termination codon TM region. This particular allele encode soluble, secreted form molecule. addition, investigated 77 Japanese patients with Behcet disease, which known be associated HLA-B51. consisting 6 repetitions GCT/AGC was present at significantly higher frequency patient group (Pc = 0.00055) than control population. Furthermore, (GCT/AGC)6 all B51 positive 13 negative patients. These results suggest possibility primary association disease rather HLA-B.