Early-onset familial Alzheimer’s disease (EOFAD) is a rare but important type of Alzheimer’s disease (AD). Asymptomatic carriers of EOFAD gene mutations harbor AD neuropathological features and are prone to develop dementia. Due to its high penetrance, neurochemistry and predictable natural history EOFAD is the ideal population for assessing the evolution of AD. Although 228 mutations have been already described for presenilin 1 (PS1), presenilin 2 (PS2) and amyloid presursor protein (APP) genes, EOFAD constitute an important population for research on the genetic basis of AD since nearly half of kindreds remains without molecular diagnosis.