Chromosome 17 and 21 aneuploidy in buccal cells is increased with ageing and in Alzheimer's disease

Alzheimer's disease (AD) is a premature ageing syndrome characterized by cognitive impairment arising from neuropathological changes occurring within specific areas of the brain. We report a 1.5-fold increase in trisomy 21 (P < 0.001) and a 1.2-fold increase in trisomy 17 (P < 0.001) in buccal cells of Alzheimer's patients compared to age- and gender-matched controls. Chromosome 17 and chromosome 21 monosomy and trisomy increase significantly with age (P < 0.001). Down's syndrome, which exhibits similar neuropathological features to those observed in AD also showed a strong increase in chromosome 17 monosomy and trisomy compared to matched controls (P < 0.001). These results suggest that an increased incidence of aneusomy for both chromosomes 17 and 21 may contribute to the aetiology of AD. We also investigated aneuploidy rates in hippocampal brain cells, which have been shown to have a low rate of cell division, which may be relevant in potential incidence of non-disjunction. However, aneuploidy rate for chromosomes 17 and 21 in the nuclei of hippocampus cells of brains from Alzheimer's patients and controls were not significantly different. These results are suggestive that the aneuploidy events investigated which are increased beyond the incidence in normal ageing may be influenced by genetic factors that may predispose to AD, but are unlikely to be a primary cause of AD brain pathology.