p15INK4b methylation correlates with thrombocytopenia, blast percentage, and survival in myelodysplastic syndromes in a dose dependent manner: quantitation using pyrosequencing study.

We investigated how the quantity of p15INK4b methylation related to International Prognosic Scoring System variables and survival in 74 patients with de novo myelodysplastic syndrome (MDS). Pyrosequencing of 11 consecutive CpG sites of the p15INK4b promotor region was performed, with the extent of CpG cytosine methylation assessed in terms of methylation level (MtL). Patients with >5% bone marrow blasts had higher MtL than patients with <5% blasts (10.1% vs. 6.1%, p=0.030, respectively). Methylation was not associated with chromosomal aberrations. The MtL of patients with thrombocytopenia were higher than patients without thrombocytopenia (11.2% vs. 6.2%, p=0.036, respectively); they were higher in patients with cytopenias in > or =2 lineages than in patients with either unilineage or no cytopenia (9.8% vs. 4.1%, p=0.036, respectively). The survival of patients with >7% MtL was worse than patients with <7% MtL (p=0.031). Heavy p15INK4b methylation in MDS is associated with IPSS predictors of poor prognosis and adverse survival.