A novel missense mutation in PSEN2 gene associated with a clinical phenotype of frontotemporal dementia

Background: In Familial Alzheimer's disease defects in three genes - the amyloid precursors protein (APP) gene on chromosome 21, the presenilin 1 (PSEN1) gene on chromosome 14 and the presenilin 2 (PSEN2) on chromosome 1- have been identified. More than 160 pathogenic missense mutations have been described in PSEN1, with wide clinic phenotypic variability. In PSEN2 only 11 missense mutations are known, in two of which (M239V and T122R) the clinical phenotype may be frontotemporal dementia-like. Methods: We present a novel PSEN2 mutation (Y231C) in an Italian patient who seven years ago, at age 55, manifested mood and behavioural disorders characterized by apathia, delusions, physical aggressive behaviour and psychomotor agitation. Language disturbances appeared one year later and mild memory loss three years later. The neuropsychological pattern suggested a main dysfunction in posterior temporal and parietal cortex. MRI showed diffuse atrophy, especially in posterior regions. Results: The genetic study showed an A-to-G mutation in exon seven of PSEN2 gene, resulting in tyrosine to cysteine substitution at residue 231. Conclusions: This new mutation confirms the variability of the phenotypes associated with PSEN2 mutations and justified the analysis of this gene in behavioural disturbances associated with degenerative dementia, at least in Italy in which PSEN2 mutations seems more frequent than in other countries.