Polymorphism of the MICA gene and risk for oral submucous fibrosis

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.

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.

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).

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