C9orf72 and amyotrophic lateral sclerosis: Abnormalities of KPNA4 also extend to human post-mortem samples, as immunostaining of frontal cortex tissue from sporadic FTD and C9orf72-ALS/FTD cases showed abnormal KPNA4 nuclear depletion or nuclear inclusions, and biochemical KPNA4 showed reduced solubility, potentially reflecting increased aggregation or impaired function (Solomon et al., 2018).