A large number of diseases occur in association with specific HLA-B or-C alleles. Recently a new gene, termed maj or histocompatibility complex class I chain-related gene A (MICA), has been identified in close proximity to HLA-B. The function of this gene is still unknown. However, it is structurally similar to HLA class I genes. MICA gene is polymorphic and is potentially associated with several diseases.

To evaluate the association of MICA gene in Korean patients with human immunodeficiency virus 1 (HIV-1) infections, Polymerase chain reaction-Sequence specific primer (PCR-SSP) was done for MICA alleles in the extracellular exons, and a microsatellite analysis for GCT repeat polymorphisms in the TM exon was also completed.

In 199 Korean healthy controls, 7 alleles were observed and the frequencies for each allele were MICA008 (44.7%), MICA0 10 (34.2%), MICA002 (31.7%), MICA004 (23.6%), MICA012 (2 1.6%), MICA009 (19.6%), and MICA007 (6.5%). When 65 HIV seropositive patients were analyzed, MICA007 allele frequency was significantly higher than in controls (15.4% vs 6.5 %, RR=2.6, p<0.04). In contrast, the frequencies of other MICA alleles and microsatellite alleles in the transmembrane region of MICA gene were not significantly different between HIV seropositive patients and controls. The tight linkage between MICA alleles in the extracellular exons and GCT repeat polymorphisms in the TM exon was observed as follows; MICA002/A9, MICA004/A6, MICA007/A4, MICA008/A5.1, MICA010/A5, and MICA012/A4 in both groups. No significant difference between patients and controls was observed in the haplotype frequencies of MICA alleles in the extracellular exons and GCT repeat polymorphisms in the TM exon.

The data suggest that immune functions related with MICA gene may affect a HIV infections.