Instead of triggering disease onset or acting as risk factors, different mutations in ALS-related genes can also act as modifiers of the disease by changing the age of clinical presentation (early VS late-onset), the evolution of the disease (e.g., fast VS slow progression), the development of certain profiles (e.g., mutations on ALS2 or mutations on DCTN1 observed within the ALS/FTD family case), the molecular changes observed, etc. Additionally, the interaction between two or more of these genes to trigger and/or modify the clinical presentation of the disease has to be taken into account. The gene discussed is ALS2; the disease is frontotemporal dementia.