APOLIPOPROTEIN-E AND ALPHA-1 ANTICHYMOTRYPSIN POLYMORPHISM GENOTYPINGIN ALZHEIMERS-DISEASE AND IN DEMENTIA WITH LEWY BODIES - DISTINCTIONSBETWEEN DISEASES

The possibility of gene interactions in Alzheimer's disease (AD) has b een suggested by the finding of an association of the AA genotype of t he alpha-1 antichymotrypsin (AACT) gene and the apolipoprotein E (apoE ) epsilon 4/4 genotype in AD. We tested this possibility by genotyping a large series of clinically and neuropathologically confirmed cases of AD and a series of cases with dementia with Lewy bodies (DLB) with a matched control group for the AACT locus and apoE. ApoE genotyping s howed the established finding of an increased frequency of the apoE ep silon 4 allele in AD and in DLB. The AD and DLB groups differed betwee n each other with a higher epsilon 2 allele frequency and a reduced in cidence of the epsilon 4/4 genotype in DLB. Differences in the apoE fr equencies may account for some of the differences between the two dise ases. No association was found for the AACT A allele in AD or DLB in t he groups as a whole or when stratified with respect to apoE, with the exception of a trend showing an increased incidence of the apoE epsil on 4/4 AACT AA genotype combination in AD patients (chi(2) = 3.18, p = 0.07), although in DLB this was not apparent (chi(2) = 0.0, p = 1.0). The AACT A allele is not a major risk factor for late-onset AD or DLB .