High frequency of human leukocyte antigen class II DRB1*1602 haplotype in Greek patients with myelodysplastic syndrome and of DRB1*1501 in the low-risk subgroup.

Myelodysplastic syndromes (MDS) comprise a heterogenous group of clonal hematopoietic disorders in which the immune-mediated pathogenetic mechanisms are under investigation. Overrepresentation of human leukocyte antigen (HLA)-DR2 and its serologic split HLA-DR15 has been associated with low-risk MDS in certain ethnic groups and has been proposed as a predictive factor for a favorable response to immunomodulatory treatment. Because the HLA-DRB1*15 haplotype does not predominate in the Greek population, we investigated the frequency of HLA-DRB1 alleles among 114 patients of Greek origin suffering from various types of MDS: 36 refractory anemia (RA), 24 refractory anemia with ringed sideroblasts (RARS), 19 refractory anemia with excess of blasts (RAEB), 14 refractory anemia with excess of blasts in transformation (RAEB-t), 14 chronic myelomonocytic leukemia, and 7 hypoplastic MDS patients. HLA-DRB1 molecular typing was performed with polymerase chain reaction-sequence specific oligonucleotides and results were compared with that from a previously reported control Greek population. HLA-DRB1*1602 was the only allele that was significantly overrepresented in Greek MDS patients as a whole, whereas HLA-DRB1*1501 allele frequency was significantly higher in Greek patients with low-risk myelodysplasia. Our results suggest the possible value of HLA-DR15 and HLA-DR16 as determinants for immunomodulatory interventions, at least for Greek patients with low-risk MDS.