Validation of ZAP-70 methylation and its relative significance in predicting outcome in chronic lymphocytic leukemia

ZAP-70 methylation 223 nucleotides downstream of transcription start (CpG+223) predicts outcome in chronic lymphocytic leukemia (CLL), but its impact relative to CD38 and ZAP-70 expression or immunoglobulin heavy chain variable region (IGHV) status is uncertain. Additionally, standardizing ZAP-70 expression analysis has been unsuccessful. CpG+223 methylation was quantitatively determined in 295 untreated CLL cases using MassARRAY. Impact on clinical outcome vs CD38 and ZAP-70 expression and IGHV status was evaluated. Cases with low methylation ( 0.90). Thus, ZAP-70 CpG+223 methylation represents a superior biomarker for TT and OS that can be feasibly measured, supporting its use in risk-stratifying CLL. •Methylation analysis at ZAP-70 CpG+223 in CLL provides superior prognostic information vs IGHV status or CD38 or ZAP-70 expression.•A pyrosequencing method for the feasible assessment of CpG+223 methylation in CLL samples is provided.