Novel epigenetic biomarkers for hematopoietic cancer found in twins.

BACKGROUND AND PURPOSE This article aims to identify epigenetic markers and detect early development of hematopoietic malignancies through an epigenome wide association study of DNA methylation data. MATERIALS AND METHODS This register-based study includes 1,085 Danish twins with 31 hematopoietic malignancies and methylation levels from 450,154 5'-C-phospate-G-3' (CpG) sites. Associations between methylation levels and incidence of hematopoietic malignancy is studied through time-to-event regression. The matched case-cotwin design, where one twin has a malignancy and the cotwin does not, is applied to enhance control for unmeasured shared confounding and false discoveries. Predictive performance is validated in the independent Older Finnish Twin Cohort. RESULTS AND INTERPRETATION We identified 67 epigenetic markers for hematopoietic malignancies of which 12 are linked to genes associated with hematologic malignancies. For some markers, we discovered a 2-3-fold relative risk difference for high versus low methylation. The identification of these 67 sites enabled the formation of a predictor demonstrating a cross-validated time-varying area under the curve (AUC) of 92% 3 years after individual blood sampling and persistent performance above 70% up to 6 years after blood sampling. This predictive performance was to a large extent recovered in the validation sample showing an overall Harrell's C of 73%. In conclusion, from a large population representative twin study on hematopoietic cancers, novel epigenetic markers were identified that may prove useful for early diagnosis.