Polymorphism of the MICA gene and risk for oral submucous fibrosis.

BACKGROUND: Oral submucous fibrosis (OSF), an insidious, pre-cancerous, chronic disease that may affect the entire oral cavity and sometimes extend to the pharynx has been reported to be associated with immune function. The major histocompatibility complex (MHC) class I chain-related gene A (MICA) is expressed by keratinocytes and other epithelial cells, and its encoded protein interacts with gamma/delta T-cells localized in the submucosa. The MICA gene has a triplet repeat (GCT) polymorphism in the transmembrane domain resulting in five distinct allelic patterns.

METHODS: We analyzed MICA polymorphism in 80 OSF patients and 351 randomly selected unrelated controls by using the ABI Prism 377-18 DNA sequencer (Applied Biosystems) to analyze the sample DNA PCR products. The number of microsatellite repeats was estimated with Genescan 672 software (Applied Biosystems) with a standard size marker of GS-350 TAMRA.

RESULTS: The phenotype frequency of allele A6 of MICA in subjects with OSF was significantly higher than that in controls (OR = 3.48; 95% CI = 1.8-6.71; P = 0.0002), as was the frequency of the allele (OR = 2.65; 95% CI = 1.44-4.86; P = 0.001).

CONCLUSION: The results suggest that allele A6 in MICA might confer a risk for OSF.