OPTN and frontotemporal dementia: The current work revealed that MAPT–GRN, HLA-DRA–CTSC, TMEM106B and C9orf72–VCP–UBQLN2–OPTN clustered in interesting modules in the frontal and/or temporal cortex and that, particularly on the basis of functional annotation and pathway analyses, three main biological processes with a direct relation to FTD-genes hold relevance to the pathogenesis of FTD: i) DNA & chromatin biology; ii) immune & lysosomal processes, and; iii) protein meta/catabolism.