C9orf72 and amyotrophic lateral sclerosis: Moreover, biochemical analysis and immunohistochemical stainings revealed lowered HNRNPK expression in patient spinal cord tissue and fibroblasts from sporadic ALS and familial TDP-43 ALS cases [48, 49], whereas our data and publically available datasets indicated unaltered transcript levels in C9orf72 ALS patient iPSC-derived motor neurons and frontal cortex [44, 57, 61].