Monarch Disease Ontology id MONDO_0011913 (Alzheimer disease 3) is alzheimer's disease with an early onset (starts before the age of 65). It is caused by mutations in the PSEN1 gene. Also known as: AD3, Alzheimer disease 3, early onset, Alzheimer disease familial 3, Alzheimer disease type 3, Alzheimer disease, protection against, due to APOE3-Christchurch, Alzheimer disease, type 3, Alzheimer disease, type 3, with spastic paraparesis and apraxia, Alzheimer disease, type 3, with spastic paraparesis and unusual plaques.