Fragile sites, Alzheimer's disease, and aging

The fragile site expression under conditions of folate deprivation was compared in the chromosomes from 5 Alzheimer's disease (AD) female patients, 5 healthy elderly females and 5 healthy young females. Although different fragile sites were observed in the three groups, nevertheless, more similarities were found between the AD patients and elderly normal donors. The only fragile site common to all groups was 3p14. This site was the most frequent in the young donors group. In both AD and elderly control groups we observed a higher frequency of fragility in 6p21, but not in the young controls. Other interesting fragility points observed in these two groups were: 6q21 and 14q24 (in the AD patients) and 9q13, 14q24 and 17q21 (in the healthy aged). 6p21 and 17q21 have been proposed as 'new' fragile sites. We confirm the existence of these fragile sites and comment that in these bands the genes MTBT2 and MTBT1, which are microtubule (beta) associated protein tau-like and tau 1, respectively, are mapped. The tau protein is a component of paired helical filaments which accumulate in degenerating neurons in the brain of patients with AD and with less intensity of normal elderly individuals.