This is important to explore in longitudinal studies traversing phenoconversion as some genotypes, such as C9orf72, may evolve into distinctly different clinical phenotypes along the ALS-FTD spectrum (Chipika et al., 2020; Omer et al., 2017; Chipika et al., 2021). This evidence concerns the gene C9orf72 and amyotrophic lateral sclerosis.