Clinical characterization of a presenilin 1 mutation (F177S) in a family with very early-onset Alzheimer's disease in the third decade of life.

BACKGROUND: Early-onset familial Alzheimer disease (AD) is an autosomal dominant disorder caused by mutations in the amyloid precursor protein, presenilin 1 (PSEN1), or presenilin 2 gene. The objective of this study was to characterize the phenotype in a large family with a PSEN1 F177S mutation by performing detailed clinical assessments, neuroimaging, and neuropathological analysis. METHODS: In two subjects, clinical and neuropsychological assessments, structural magnetic resonance imaging, F-18-2-fluoro-2-deoxy-D-glucose positron emission tomographic imaging, AD biomarkers in cerebrospinal fluid and genetic analysis were available. In three deceased affected subjects, medical records were reviewed. In one subject, a complete neuropathological examination was available. RESULTS: Cognitive impairment and neurological symptoms developed homogeneously around 30 years of age and worsened rapidly. All subjects died about 7 years (range, 6-8 years) after disease onset before 40 years of age. All technical diagnostic information (neuroimaging, cerebrospinal fluid) were typically for AD. Neuropathology showed abundant neuritic plaques and neurofibrillary tangles, typical of severe AD. Antidementia treatment in one subject did not alter the length of survival. CONCLUSIONS: The PSEN1 F177S mutation leads to typical AD starting at age 30 and a homogeneous phenotype with rapid cognitive decline and prominent neurological symptoms. Excessive amyloid beta 42 production in the brain cortex corresponds well with other PSEN1 mutations.