C9orf72 and COVID-19: Since the aim of the second part of our work was not the comparison between COVID-19 patients and the general population but the confirmation of our hypothesis that harboring alleles with more than 10 repeats in the C9orf72 gene may be a risk to develop a more severe form of disease, we considered only COVID-19 patients stratified in severely affected ones that received MV or NIV during hospitalization and non-hospitalized subjects (asymptomatic or with very mild symptoms).