In a subset of pre-symptomatic C9orf72 mutation carriers aged over 40 with a family history of ALS, reduced FA in the CSTs was also detected at baseline [47], suggesting that CST FA alterations in C9orf72 carriers may help to identify those who are more likely to convert to ALS rather than frontotemporal dementia [47]. Here, C9orf72 is linked to amyotrophic lateral sclerosis.