OPTN and frontotemporal dementia: Interestingly, we noticed that all genes mentioned above (and PPI interactors of VCP, UBQLN2, OPTN or C9orf72) were included together with the spectrum FTD-genes in the gene lists supporting GO terms indicating functions pointing to protein catabolism pathways and cytoplasmic protein transport and/or vesicle trafficking as highlighted in Additional file 2: Tables S11 and/or S14.