The Quantitative Methylation Pattern Of ID4 Gene In Myelodysplastic Syndrome

Myelodysplastic syndrome (MDS) is a heterogeneous group of clonal stem cell disorder characterized by abnormal differentiation and maturation of myeloid cell. As a hematological malignant disease,30% MDS patients eventually transform to acute myeloid leukemia (AML). MDS is often difficult to distinguish from hematological benign diseases with unilineage or multilineages cytopenia such as aplastic anemia (AA) both in clinic and laboratory. In recent years genetic markers were shown to be very useful to this problem. The MDS patients without genetic changes need a reliable new marker such as epigenetic biomarkers. The initial of MDS is believed to be a multistep process requiring gene expression abnormality to accumulate malignant clone proliferation and differentiation inhibition. Gene expression abnormality is regarded as an event requiring the accumulation of both genetic and epigenetic alterations. Aberration of epigenetic regulation especial methylation plays a functionally equivalent role to genetic alterations, and is focused on gene silence mechanism. The aberrant hypermethylation of the promoter region of ID4 gene has a relationship with the initial and development of many kinds of hematological malignant diseases. In addition, ID4 is also involved in regulation of cell cycle, cell proliferation and differentiation by several pathway such as aberrant hypermethylation of the promoter region。A recent research showed a notable relationship of ID4 gene methylation status with the initial and development of MDS。The objective was to investigate the quantitative methylation status of ID4 gene in MDS and identify its roles in diagnosis, prognosis, treatment effect and microresidual disease (MRD) of MDS.This study was sought to characterize ID4 gene methylation in MDS and aplastic anemia (AA). The methylation status of ID4 was analysed by bisulfite sequencing PCR (BSP) and quantitative real-time methylation-specific PCR (methylight) in 100 MDS patients and 31 AA patients, positive sites frequency of ID4 gene using BSP for the MDS patient 29.38% (141/480) are higher for the AA patient 8.125% (39/480) significantly (p=0.000, figure 1).MDS patients group had higher ID4 gene methylation positive(27%) rate and methylation level [0.21 (0-3.79)] than AA patients group. Furthermore, the significanct differences of MDS patients with low BM (bone marrow) blast counts, normal karyotype or hypoplatic MDS and AA had the same trend. Many MDS patients had no identical genetic markers (40% ) but with ID4 hypermethylation (29% ).Combining genetical and epigenetical markers were performed in more MDS patients (58% ) to be distinguished from AA. These results showed that detection of ID4 methylation both positive rate and degree coulde be a useful new biomarker for MDS diagnosis.The Inhibitor of DNA binding 4 (ID4) protein is supposed a tumor suppressor for hematology malignant. Hypermethylation of ID4 gene may play an important role in initial and development of myelodysplastic syndrome (MDS) and leukemia. The quantitative detection of ID4 gene methylation alteration should be established in order to evaluate disease progression more effectively and exactly. This study was conducted to determine changes of ID4 gene methylation level in MDS risk subtypes and sequential samples using methylight. ID4 methylation occurred in 27 patients (27% ), and was more frequent and high degree in patients with advanced stages and high-risk subgroups as WHO (p=0.000, p=0.000) and IPSS (p=0.002, p=0.007). Both the methylation positive rates and methylation levels had significant differences in NBM, MDS patients and patients with MDS-AL (p=0.000, p=0.000). One patient with 5 times samples had sharp increase of ID4 methylation level during disease progression and disappeared after haematopoietic stem cell transplantation or demethylation regents. This is the first report to demonstrate the clinical significant of ID4 gene methylation in MDS sequential samples and the different methylation status of ID4 gene among NBM, MDS and leukemia. Our findings suggest that ID4 may play a key role in MDS progression.In a word, ID4 may be a new biomarker to evaluate MDS development, treatment effect even microresidual disease (MRD)...