These results suggest that silencing of p15(INK4B) gene expression by epigenetic modification such as promoter hypermethylation plays a role not only in the initiation of MM but also in plasma cell malignant transformation, disease progression, and development.
Selective methylation was found in 19% for p16(INK4a), 36% for p15(INK4b), and 6.5% for both genes in MGUS, and frequencies were similar in MM suggesting that methylation of these genes is an early event, not associated with transition from MGUS to MM. p15(INK4b) and p16(INK4a) gene methylation might contribute to immortalization of plasma cells rather than malignant transformation in the natural history of MM.