Targeted deep sequencing was performed using the target gene panel consisting of 26 genes evidently or potentially associated with MDS (DNMT3A, TET2, EZH2, RUNX1, ASXL1, STAG2, CBL, TP53, SRSF2, SF3B1, U2AF1, LAMB4, DNMT1, ETV6, KRAS, NF1, NPM1, NRAS, PRPF8, IDH1, IDH2, JAK2, FLT3, SETBP1, ATRX, and ZRSR2) [10–14, 16–20]. The gene discussed is TET2; the disease is myelodysplastic syndrome.