RBM8A and amyotrophic lateral sclerosis: Beyond ALS8, VAPB-mediated ER-mitochondria contact sites may be relevant to ALS in general, as suggested by the effect of two ALS-linked gene products, Tar-DNA binding protein 43 (TDP43 or TARDBP) and fused in sarcoma (FUS), on the VAPB-PTPIP51 tether.