Unusual association of the DRB4 null allele, DRB4*0103102N, with HLA DRB1*0402 in a sample of Austrian patients

Tissue typing for HLA class II antigens is routinely performed by serologic al, and/or DNA-based methods. Accuracy, absence of cross-reactivity and con trollable level of resolution are striking advantages of molecular methods. However, a disadvantage of molecular typing, compared to serological metho ds, is the identification of unexpressed alleles. Whereas serology allows a more or less direct insight into antigen presence, molecular biology is an indirect method and results must also be interpreted by considering the bi ological pathways of protein expression. We believe that identification of nonexpressed MHC alleles is of importance for transplantation, since nonexp ressed MHC allele positive individuals could give rise to antibody formatio n against the respective expressed MHC product in donor tissue. Usually, th e nonexpressed DRB4*0103102N is encountered in association with DRB1*0701-D QBI*03032, which facilitates correct DNA typing. Here we describe the unusu al association of this unexpressed DRB4*0103102N, with DRB1*0402-D61B1*0302 in a sample of Austrian patients.