C9orf72 and amyotrophic lateral sclerosis: Finally, to provide further evidence that ER-Golgi trafficking is perturbed in C9orf72-ALS, we examined ER-derived vesicles in human patient derived fibroblasts and post-mortem patient tissues using immunochemical staining for Sec31A as a marker of ER-derived vesicles and vesicle clusters, in which multiple individual COPII vesicles often cluster together.