Relationship between alpha(1)-antichymotrypsin microsatellite and apolipoprotein E in Alzheimer's disease

The amyloid associated proteins apolipoprotein E (apoE) and alpha(1)-antich ymotrypsin (ACT) have been shown to enhance the formation of beta-amyloid f ilaments in vitro. Amyloid deposits are present in the brain of Alzheimer's disease (AD) patients and of elderly individuals. Genetic studies in AD ha ve identified the allele epsilon 4 of apoE as a major risk factor for AD, h owever this allele is neither necessary nor sufficient for the manifestatio n of the disease. A bi-allele polymorphism in the signal region of the ACT gene and a repeat microsatellite region at the start of the ACT gene have b een postulated to be associated with AD. Our investigation, carried out in post-mortem brain tissue from 56 histologically confirmed AD patients and 7 0 histologically confirmed controls, showed an association between the apoE epsilon 4 allele and AD but no association between the ACT bi-allele polym orphism. Previous results showing an increased risk for AD in individuals p ossessing apoE epsilon 4 and allele 10 of the ACT microsatellite was not fo und in the present study and this could be explained by the non-random asso ciation of the ACT A10 allele with apoE epsilon 4 in both the control and A D groups. It was not possible, therefore, to separate the effects of each o f the two alleles.