For early-onset autosomal dominant AD, mutational screening is recommended in the sequence: PSEN1, APP, and if negative, PSEN2, to support genetic counseling.Consider genetic screening in sporadic cases of early-onset AD.Testing for PGRN and MAPT mutations is clearly indicated and useful for genetic counseling in autosomal dominant FTLD. Testing may also be considered in sporadic FTLD cases, although with a lower diagnostic yieldIf CADASIL is clinically suspected, direct sequencing of exons 3 and 4 of the Notch3 gene is recommended as an initial test. Here, GRN is linked to Alzheimer disease.