A presenilin-1 mutation (T245P) in transmembrane domain 6 causes early onset Alzheimer's disease.

We report a presenilin-1 mutation (T245P) in a Japanese-American family with autosomal dominant Alzheimer's disease with an onset age in the early 40s. The early clinical features were remarkable for their purely amnestic nature. The position of the mutation is in the transmembrane domain that harbors the aspartic acid residue which is believed to be part of the active site of gamma-secretase.