Peripheral blood cell‐free DNA is an alternative tumor DNA source reflecting disease status in myelodysplastic syndromes

Genetic alterations in myelodysplastic syndromes (MDS) are critical for pathogenesis. We previously showed that peripheral blood cell‐free DNA (PBcfDNA) may be more sensitive for genetic/epigenetic analyses than whole bone marrow (BM) cells and mononuclear cells in peripheral blood (PB). Here we analyzed the detailed features of PBcfDNA and its utility in genetic analyses in MDS. The plasma‐PBcfDNA concentration in MDS and related diseases (N = 33) was significantly higher than that in healthy donors (N = 14; P = 0.041) and in International Prognostic Scoring System higher‐risk groups than that in lower‐risk groups (P = 0.034). The concentration of plasma‐/serum‐PBcfDNA was significantly correlated with the serum lactate dehydrogenase level (both P < 0.0001) and the blast cell count in PB (P = 0.034 and 0.025, respectively). One nanogram of PBcfDNA was sufficient for one assay of Sanger sequencing using optimized primer sets to amplify approximately 160‐bp PCR products. PBcfDNA (approximately 50 ng) can also be utilized for targeted sequencing. Almost all mutations detected in BM‐DNA were also detected using corresponding PBcfDNA. Analyses using serially harvested PBcfDNA from an RAEB‐2 patient showed that the somatic mutations and a single nucleotide polymorphism that were detected before allogeneic transplantation were undetectable after transplantation, indicating that PBcfDNA likely comes from MDS clones that reflect the disease status. PBcfDNA may be a safer and easier alternative to obtain tumor DNA in MDS. PBcfDNA concentration is significantly higher in IPSS higher risk MDS patients than that in lower risk patients. PBcfDNA can be a safer and easier alternative tumor DNA source in MDS for mutation analyses using not only conventional Sanger sequence strategy but also next generation targeted sequencing strategy.