Ataxic variant of Alzheimer’s disease caused by Pro117Ala PSEN1 mutation

Presenilin 1 (PSEN1) mutations account for the majority of cases of autosomal dominant early onset Alzheimer’s disease (ADEOAD).1 2 The PSEN1 gene encodes for a 467 amino acid transmembrane protein which functions as a subunit of the γ-secretase complex that cleaves amyloid precursor protein to generate the Aβ amyloid peptide. More than 160 different mutations have been reported (www.molgen.ua.ac.be/ADMutations) with a great diversity of phenotypes: very early age of onset, early myoclonus seizures, parkinsonism, spastic paraplegia associated with “cotton wool plaques” or rare frontotemporal variant of AD. Ataxia has been rarely described during the course of ADEOAD caused by PSEN1 mutations. Ataxia and psychiatric signs were recently reported as initial symptoms associated with a PSEN1 Ser170Phe mutation.3 We report three patients from the same family with early prominent severe ataxia associated with dementia caused by a novel PSEN1 mutation. ### Patient III2 A 35-year-old woman (fig 1) was seen for writing and balance difficulties, with memory complaints. All three symptoms occurred contemporaneously 1 year previously. Examination showed severe ataxia with instability, marked dysarthria and dysmetria with intention tremor, brisk reflexes and rare myoclonus. Neuropsychological assessment, including Mini Mental Scale (score 22/30), Grober and Buschke Learning Test (GBVLT) (delayed total …