Somatic mutation of HLA-DRB1*04:03 in a patient with myelodysplastic syndrome at diagnosis.

Loss or decrease in expression of human HLA caused by somatic mutations of HLA genes has been reported in various malignancies. However, mutations in the HLA-DR gene have been rarely noted in hematologic malignancies. Here, we report a case of myelodysplastic syndrome (MDS) with a novel point mutation in exon 2 of the HLA-DRB1*04:03 gene pertaining to a silent mutation (c.357A > T[p.Thr=]). When compared before and after anticancer drug treatment and to the results from the full HLA-matching sibling donor, mutation of the HLA-DRB1 gene suggests clonal evolution. In conclusion, we report a new DRB1*04:03 mutation in an MDS patient at diagnosis that results in a synonymous substitution with unknown clinical impact.