OTX2 and digestive system neoplasm: The analysis showed altered NRSEs associated with the following genes involved in neuronal processes: PCDHG cluster, BARHL2, OTX2, NXPH1 and RARA. Two others selected NRSEs are associated with LOC93429, a long non-coding RNA, and the pseudogene HCG22. Interestingly, these NRSE presented opposite DNA methylation pattern between PA and gastrointestinal tumours, whereas no alteration in these NRSE regions was detected in CLL, suggesting a different regulation mechanism in tumour types.