Among AD conditions, detected variants were de novo in all cases except the 2 related patients with the FHF1 variant (suspected germline mosaicism) [43], 1/7 cases with GNAO1 variants (suspected germline mosaicism) [15], 2/17 unrelated cases with paternally inherited SCN2A variants [36,37], and 1 KCNQ2 variant, inherited from the affected mother [22]. Here, SCN2A is linked to Alzheimer disease.