Increased frequency of DR2 in patients with aplastic anaemia and increased DR sharing in their parents

68 patients with aplastic anaemia, their parents and healthy siblings were typed for HLA-A, B and DR antigens. Among the patients there is an overrepresentation of DR2. The parents of affected children show an increased compatibility at the DR locus. This situation could favour the expression of recessive gene(s) involved in haematopoiesis and located in the HLA locus.