As the discovery of the Alzheimer disease (AD) genes, APP, PSEN1, and PSEN2, in families with
autosomal dominant early-onset AD (EOAD), gene discovery in familial EOAD came more or less to
a standstill. Only 5% of EOAD patients are carrying a pathogenic mutation in one of the AD genes or
a APOE risk allele ε4, most of EOAD patients remain unexplained. Here, we aimed at summarizing
the current knowledge of EOAD genetics and its role in ongoing approaches to understand the
biology of AD and disease symptomatology as well as developing new therapeutics. Next, we
explored the possible molecular mechanisms that might underlie the missing genetic etiology of
EOAD and discussed how the use of massive parallel sequencing technologies triggered novel
gene discoveries. To conclude, we commented on the relevance of reinvestigating EOAD patients
as a means to explore potential new avenues for translational research and therapeutic discoveries.
2016 The Authors. Published by Elsevier Inc. This is an open access article under the CC BY-NCND
license