alpha-1-Antichymotrypsin polymorphism in the gene promoter region affects survival and synapsis loss in Alzheimer's disease.

One-hundred-thirty-tree patients with neuropathologically confirmed Alzheimer's disease (AD) were genotyped for the polymorphic regions in the apolipoprotein Eepsilon (APOE)and a new polymorphism in the promoter region of the alpha-1-antichymotrypsin (ACT) gene. The ACT TT genotype was associated with a longer survival of AD patients, and among patients with the APOE epsilon4 allele, this genotype increased the duration of the disease. The ACT TT genotype was also associated with a late age at onset of the disease and a delayed age at death in patients without the APOE epsilon4 allele. This latter group of patients also showed increased levels of synaptophysin from the mid-frontal (MF) cortex area. ACT appears to play complex, multiple roles on AD and to affect synaptic plasticity in the AD brain of patients without the allele APOE epsilon4 allele.