LAUSR

Single gene mutations in the RAS pathway are uncommon and of unknown significance in myelodysplastic syndrome (MDS) patients, RAS pathway‐related gene mutations (RASwaymut) as a whole may be significant and require further elucidation. The clinical and molecular data of 370 MDS patients who were newly diagnosed between 1 November 2016 and 31 August 2020 in our hospital were collected and retrospectively reviewed. RASwaymut were detected in 57 (15.41%) patients. Higher median percentage of marrow blasts (2% vs. 1%, P = 0.00), more co‐mutated genes (4, interquartile range [IQR]: 2–5. vs. 2, IQR:1–4, P = 0.00), more higher risk patients according to international prognostic scoring system‐revised (IPSS‐R) (80.70% vs. 59.11%, P = 0.002) as well as higher acute myeloid leukemia transformation rate (35.09% vs. 14.38%, P = 0.02) were observed in patients with RASwaymut when compared to those with wild type RAS pathway‐related genes (RASwaywt). The most frequent co‐mutated genes were ASXL1 (28.6%), TET2 (23.2%), U2AF1, RUNX1, TP53 (14.3%); DNMT3A (12.5%), among which ASXL1 mutation rate were significantly higher than those with RASwaywt (p < 0.05). RASwaymut had no significant effect on response to disease‐modifying treatment in MDS patients. However, Overall survivals (OS) of RASwaymut patients were significantly shorter than those with RASwaywt (16.05 m. vs. 92.3 m, P = 0.00), especially in patients with marrow blasts less than 5% (P = 0.002), normal karyotype (P = 0.01) and lower risk (P = 0.00). While multivariate prognostic analysis showed that RASwaymut co‐mutated with TET2 was an independent poor prognostic factor for all MDS patients (P = 0.00, hazrad ratio [HR] = 4.77 with 95% confidence interval [CI]: 2.4–9.51) and RASwaymut patients (P = 0.02, HR 2.76, 95% CI 1.21–6.29). In conclusion, RASwaymut was associated with higher IPSS‐R risk, higher incidence of leukemic transformation thus shorter OS in MDS patients, it could be viewed as a whole to predict poor prognosis. Co‐mutation with TET2 may promote disease progression and was an independent poor prognostic factor in MDS patients.