Prognostic factors in C9orf72 amyotrophic lateral sclerosis

The discovery of the C9orf72 hexanucleotide repeat expansion heralded significant advancement in the understanding of amyotrophic lateral sclerosis (ALS).1 ,2 Critically, the C9orf72 mutation represents the most common genetic cause of ALS (up to 50% of familial and 20% of sporadic ALS), responsible for the majority of motor and cognitive manifestations across the ALS–frontotemporal dementia (FTD) continuum.3–5 Pathologically, the C9orf72 mutation is associated with TDP-43 protein aggregation, the hallmark of ALS cases and is also present in 50% of FTD. The exact function of the normal C9orf72 protein remains undefined; however, it seems to play a major role in cellular trafficking, specifically in neurons. The loss of function …