LACK OF HLA-DR2-ASSOCIATED DRB1 GENE IN A FAMILY

HLA-DR51 haplotypes co-express one DRB1 (B115 or B1*16) gene and one DRB5 gene. These haplotypes also carry two pseudogenes (DRB6 and DRB9) . During routine HLA typing for transplantation, we observed an unexpe cted DR51 haplotype in two subjects (mother and daughter) in a family. Serological typing showed that these subjects are positive for DR51 a nd DQ6 but negative for DR15 and DR16. Investigations of genomic DNA b y molecular techniques showed that these individuals carry DRB50101, DRB602 and DQB1*0602 genes, whereas the DRB1 gene associated with eit her DR15 (B11501 to B1*1504) or DR16 (B1*1601 to B1*1606) was not det ected in the mother and daughter. It is possible that the new haplotyp e, DQB10602, DRB6*02, DRB5*0101, arose by deletion of DR2-associated DRB1 gene.