Clinical Significance Of Molecular Genetics In 634 Patients With Myelodysplastic Syndrome

Objectives:To investigate the association between cytogenetic and molecular features with classification,disease progress and prognosis in patients diagnosed with primary myelodysplastic syndromes(MDS).Methods:634 patients with de novo MDS from the first affiliated hospital of medical school,Zhejiang University were enrolled in the retrospective analysis during a period from June 2008 to May 2018.Follow-up study was also conducted.The clinical variables including gender,age,blood cell counts,bone marrow blast percentage,karyotypes and WHO subtypes,as well as IPSS-R risk stratification are evaluated.To analyze the relationship between clinical variables and chromosomal abnormalities in MDS patients in this study;genomic DNA was extracted from bone marrow mononuclear cell samples and then screened by High-Throughput Sequencing for 15 MDS-related genes,including TP53、EZH2、SF3B1、U2AF1、NRAS、DNMT3A、IDH1、IDH2、TET2、CBL、ETV6、JAK2、SRSF2、RUNX1 and ASXL1.The relationships between clinical variables and different gene mutations were evaluated respectively.Univariate and multivariate analyses were performed to determine the potential variables with relation to poor prognosis.Results:38.6%(245/634)MDS patients present abnormal karyotypes.The most common abnormal karyotypes were+8(12.0%)、-5/5q-(10.6%)、-7/7q-(7.7%)、20q-(6.3%)、-13/13q-(2.8%)、-11/11q-(2.7%)、-18(2.5%)、-Y(2.2%)、-3(2.1%).The incidence of both karyotypic abnormalities and complex chromosomal abnormalities in MDS-EB group was higher than that in non-MDS-EB group(p<0.01).Analysis based on IPSS-R Scoring System had shown that advanced risk stratification gradually enhanced the incidence of karyotypic abnormalities(p<0.001).+8 was the most common abnormal karyotype and was present in 31.0%(76/245)of the patients with abnormal karyotypes.Isolated+8 more frequently presented in women(p=0.02),higher-risk patients(p<0.001),or patients with normal hemoglobin(p=0.02).Among patients with+8,patients having a combination of other abnormal karyotypes had a worse prognosis than patients with isolated+8(p=0.02).Patients with isolated+8 showed no difference from patients with normal karyotype in prognosis(p=0.35).438 patients were molecularly profiled by mutational analyses of 15 MDS-relevant genes,including TP53、EZH2、SF3B1.U2AF1.NRAS、DNMT3A、IDH1、IDH2.TET2、CBL、ETV6、JAK2、SRSF2、RUNX1 and ASXL1.Mutations were present in 45.9%of the patients in this study.The most common mutated genes were SF3B1(n=46,10.5%),U2AF1(n=46,10.5%),TP53(n=27,6.2%),TET2(n=26,5.9%),ASXL1(n=21,4.8%),RUNX1(n=21,4.8%),DNMT3A(n=18,4.1%),SRSF2(n=18,4.1%),IDH1(n=12,2.7%),IDH2(n=11,2.5%).Splice gene mutations were the most frequent molecular aberrations,detected in 54.7%of patients.SF3B1 mutations were more common in patients with MDS-RS,bone marrow blasts<5%,or IPSS-R lower-risk(p<0.001).SRSF2 mutations were more common in patients with normal karyotype(p=0.001).all mutations of U2AF1 were localized in the S34 or Q157 zinc finger domains.Patients with mutated IDH2 had a higher frequency of normal hemoglobin in comparison with patient without(45.5%vs.19.0%,p=0.02).Normal platelets were associated with mutated SF3B1 or JAK2(p<0.05).NRAS mutations only occurred in patients with MDS-EB(p=0.04).TP53 and DNMT3A mutations were more common inhigher-risk MDS patients(p<0.01).The frequencies of TP53 mutations increased with the risk grades of karyotypes in IPSS-R(p<0.001).Univariate analysis showed that the overall survival(OS)decreased gradually with the increase of IPSS-R risk stratification(p<0.001).Patients with SF3B1 mutations lived a longer life than patients without SF3B1(p=0.002).The survival of the patients with TP53 mutations was worse compared with patients without TP53 mutations(p=0.009).Multivariate analysis indicated that male,age≥60 years,chromosome 7 abnormality,IPSS-R risk group,U2AF1 mutations were independent prognostic factors(p<0.05).Higher conversion to secondary acute myeloid leukemia(sAML)was associated with older age(age≥60 years),male,gene number,or IPSS-R risk group(p<0.05).SF3B1 mutation was an independent prognostic factor for longer survival and less transformation to secondary acute myeloid leukemia(sAML)(p<0.01).Conclusions:38.6%(245/634)MDS patients had abnormal karyotypes.+8 was the most common type and present in 31.0%(76/245)patients with abnonnal karyotypes.SF3B1 mutations were more common in patients with MDS-RS,bone marrow blasts<5%,or IPSS-R lower-risk.Splice gene mutations were the most frequent molecular aberrations.SF3B1 mutations are more common in MDS-RS,bone marrow blasts<5%,and IPSS-R patients at lower risk.SRSF2 mutations were more common in patients with normal karyotype.Normal platelets were associated with mutated SF3B1 or JAK2.NRAS mutations only occurred in patients with MDS-EB.TP53 and DNMT3A mutations were more common in higher-risk patients.Patients not exclusively with+8,had a worse prognosis than with isolated+8.Mutated SF3B1 was independently associated with favorable survival and less conversion to sAML.Multivariate analysis indicated that male,age≥60 years,chromosome 7 abnormality,IPSS-R risk group,U2AF1 mutations were independent prognostic factors.Higher conversion to sAML was associated with older age(age≥60 years),male,gene number or IPSS-R risk group.This study showed that cytogenetic and molecular abnormalities play critical roles in prognosis of MDS.