Characterization of the MICA polymorphism by sequence-specific oligonucleotide probing

A large number of diseases occur in association with specific HLA-B or -C a lleles. Recently a new gene, termed major histocompatibility complex class I chain-related gene A (MICA), has been identified in dose proximity to HLA -B. The function of this gene is still unknown, but, it is structurally rel ated to HLA class I genes, is polymorphic, and is potentially associated wi th several diseases. Some DNA-based techniques have previously been describ ed to type for MICA including sequencing and single-strand conformational p olymorphism. In this paper we describe the application of sequence-specific oligonucleotide probe based typing for the analysis of the MICA gene. We u sed a set of 30 oligonucleotide probes to screen for the polymorphisms in e xons 2, 3, and 4, which account for the 16 known alleles, We report here th e typing results of MICA for 103 B-cell lines that have been well character ized for HLA and describe the linkage disequilibrium between MICA and HLA-B . Unequivocal MICA typing was achieved for 85 of the 103 cells tested, 6 ce lls gave ambiguous MICA types, and a further 12 cells showed patterns consi stent with them expressing at least one new MICA allele.