HLA-A, -B, and -DRB1 haplotype frequencies in 5-6/6 HLA matched parents

Aim In our previous study, we suggested that 19% of parents could be donors with HLA zero or one antigen mismatch of HLA-A, -B, and -DRB1 in the graft-versus-host direction, and 6.2% of parents could be 5–6/6 antigen matched donors in Japanese families. A previous study on a German population indicated that 3.5% of parents were 5–6/6 antigen matched donors. Our hypothesis was that linkage disequilibrium caused this difference, and we analyzed the relation between the haplotypes and the numbers of HLA matched loci. Methods The subjects were 1153 Japanese quartet families. Their HLA-A, -B, and -DRB1 alleles were typed by SSO method. Each family has a father, a mother, and a sibling of the patient requiring hematopoietic stem cell transplantation. The parents were divided into two groups: (i) 5–6/6 antigen matched parents ( n  = 143), and (ii) 0–4/6 antigen matched parents ( n  = 2163). In each group, NIAH (non-inherited paternal or maternal antigen haplotype) were counted and these frequencies were calculated. Results Top eight NIAH frequencies of all parents, group (i), and group (ii) are shown below. Download full-size image Conclusion There were not many tendencies for NIAH of 5-6/6 antigen matched parents to be biased against frequent haplotypes in the Japanese population.