 One B7-DR2-DQ6 derives from the fact that DR15 is a split antigen of the DR2 broad antigen serotype.The other B7-DR2-DQ1 stems from the fact that DQ1 is an alpha chain serotype that is now covered by the beta chain type DQ5 and DQ6 (DQ1 pairs with DQ5 and DQ6 by cis-haplotype pairing).There are two major subhaplotypes one that is preceded on its telomeric side by HLA A*0301 and the other by HLA A*0201.