A novel HLA haplotype containing a DRB5 gene associated with the DRB1*0103 allele.

A new hybrid haplotype, a DRB10103 allele associated with a DRB50101 allele, was found in a French Caucasoid family and has been described here. When these cells were typed by serology, contrarily to cells with the DR1 + 2s haplotype, they did not seem to be triplets. The reactivity of these cells with the DR2 allosera led to a false serological HLA-DR typing. RFLP analysis and DNA oligotyping after DR1-DRB1, DR2-DRB1 and DRB5 group-specific amplifications showed that there was no DR2-DRB1 product in these cells and demonstrated the segregation of a DR103 DR51 haplotype in the family.