Novel FUS mutations identified through molecular screening in a large cohort of familial and sporadic amyotrophic lateral sclerosis

Background and purpose: Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease. Approximately 5%-10% of cases are familial (FALS) and the remaining are sporadic (SALS). To date FUS mutations are responsible for 4%-6% of familial cases as well as 0.7%-1.8% of sporadic cases. Methods: The frequency of FUS mutations was investigated in an Italian cohort of 500 SALS and 40 FALS patients through direct sequencing of exons 5, 6, 13, 14 and 15. Results: Eight FUS mutation carriers were identified in five SALS (1%) and three FALS (7.5%), five already known and three new mutations: a de novo mutation was identified in a sporadic subject as well as the co-presence of FUS/C9ORF72 mutations in a FALS subject. The molecular and clinical details of the three patients harbouring a novel mutation (G245V, G509D and R491C) are presented here. Moreover the co-presence of the R491C mutation and C9ORF72 pathological expansion was found according to the oligogenic disease model. Conclusions: In conclusion our results revealed a higher frequency of FUS mutation carriers (7.5%) in FALS compared to literature data together with a higher presence of female gender.