Abstract

Alzheimer's disease (AD) and Parkinson's disease (PD) are genetically heterogeneous. Dipeptidyl carboxypeptidase 1 (DCP1) and butyrylcholinesterase (BCHE) genes may modify the risk of these disorders. We investigated whether common polymorphisms present in these genes operate as risk factors for AD and PD in Finnish subjects, independently or in concert with the apolipoprotein E ε4 allele (APOE ε4). Eighty late onset sporadic AD patients, 53 PD patients (34 of whom had concomitant AD pathology), and 67 control subjects were genotyped for the insertion (I)/deletion (D) polymorphism of DCP1 and the K variant ofBCHE. In logistic regression analysis, theDCP1 *I allele in combination withAPOE ε4 significantly increased the risk of AD (OR 30.0, 95% CI 7.3-123.7), compared to subjects carrying neither of the alleles. Similar analysis showed that the risk of AD was significantly increased in subjects carrying both theBCHE wild type (*WT/*WT) genotype and ε4 (OR 9.9, 95% CI 2.9-33.8), compared to those without thisBCHE genotype and ε4. Further, the risk of PD with AD pathology was significantly increased for carriers ofDCP1 *I and ε4 (OR 8.0, 95% CI 2.1-31.1). We thus conclude that, in Finns, interaction betweenDCP1 *I and ε4 increases the risk of AD as well as of PD with coexisting Alzheimer pathology, which underlines the importance of the DCP1 I/D polymorphism in the development of Alzheimer neuropathology, whereas the wild typeBCHE genotype in combination with ε4 had a combined effect with regard to the risk of AD.