LAUSR

sequencing (WGBS) data available from a subset of FL and BL (Kretzmer et al., 2015). Results: Of 64 imprinted TU represented on the array, 31 TU were significantly differentially expressed between BL and non‐BL, 16 between BL and gcBC, and 10 between non‐BL and gcBC in the MMML cohort. By RNAseq in the ICGC MMML‐Seq cohort, 68 TU were differentially expressed between BL and non‐BL (overlap with MMML cohort, 24/ 31 differentially expressed TU), 37 TU between BL and gcBC (overlap, 7/16), and 39 TU between non‐BL and gcBC (overlap, 6/10). Using WGBS, we observed in normal gcBC hemi‐methylation (mean methylation [0.3, 0.7]) typical for imprinted loci in 43/47 iDMRs. Of the 47 iDMRs, 9 co‐occurred with DMRs between BL and gcBC and only one with a DMR between FL and gcBC. Furthermore, 5/47 iDMRs overlap with such DMRs between BL and FL showing significant correlation of DNA hypermethylation and reduced expression in BL. Conclusions: Transcriptional changes of imprinted genes are common in GC‐derived B‐cell lymphomas. Nevertheless, the altered transcriptional regulation of imprinted genes seems mostly not to rely on DNA methylation changes of parent‐of‐origin‐specific DMRs.