Linkage disequilibria between HLA-B, C1_4_1, MICA and MICB.

The polymorphisms of MICA exon 5 (5 alleles), MICB intron 1 (13 alleles), C1_4_1 (6 alleles), HLA-B (29 alleles) and HLA-A (15 alleles) were investigated in a healthy German population. Sequencing was performed for the MICB alleles CA14, CA15, CA17, CA23 and CA26 isolated from different cell lines. Variation to the published sequence was observed for CA14, CA15 and for CA17. At the C1_4_1 locus a new allele (CAAA)9 was identified and confirmed by sequencing. Linkage disequilibria were investigated for two-point- and three-point-haplotypes. Although the average relative delta value correlates loosely with the physical distance from HLA-B to MICB: HLA-B-C1_4_1>HLA-B-MICA>HLA-B-MICB, there are several exceptions to this rule. Analyzing three-point-haplotypes for the segment MICB to HLA-A a wide variation of linkage disequilibria for some of the classical HLA-A, B haplotypes has been observed. While the HLA-A1, B8 haplotype displays strong relative delta values over the entire distance from HLA-A to MICB, other haplotypes have linkage disequilibria only in a limited region.