Considering all the variants detected in the selected 50 genes, we selected those with a Minor Allele Frequency (MAF) greater than 0.01 for the single variant association study in the four diagnostic groups separately (sporadic AD, sporadic FTLD, GRN, and C9orf72) as well as in the sporadic group (AD + FTLD), in the genetic group (GRN + C9orf72), and in the whole group (sporadic AD + sporadic FTLD + GRN + C9orf72). The gene discussed is C9orf72; the disease is Alzheimer disease.