Allelic variation in the intron 2 and 3 of the MICA gene

We have determined by sequencing the allelic variation in intron 2 and 3 of hte MICA gene for a total of 22 different alleles. Sequencing of introns w as performed in two directions, using DNA from homozygous cell lines from f amilies and from unrelated individuals. Intron 2 is 273 bp long and did in the alleles investigated not reveal any length polymorphism. We found a tot al of eight polymorphic positions which exhibit a strict biallelism, as it is also found in the polymorphisms for exon 2, 3 and 4 of MICA. Intron 3 is 586 bp long an required an additional set of primers placed near the middl e of this intron in order to allow a complete bidirectional sequence. In in tron 3, a total of 10 polymorphic positions were identified. Interestingly, we found two variants of the allele MICA*002 which are distinguished only by one basepair difference in intron 3. The variant MICA*002A is associated with HLA-B35 and B58, while the allele MICA*002B is associated with B38 an d B39.