Given the limitations to our knowledge of C9orf72 expression, a thorough multi-generational (minimum three generations) pedigree should be obtained, with emphasis on a history of FTD, MND, other forms of dementias, Parkinsonism, and psychiatric illnesses which are known to fall under the phenotypic spectrum of C9orf72 (Fong et al., 2012; Ducharme et al., 2017). This evidence concerns the gene C9orf72 and frontotemporal dementia.