SNPs in Aβ clearance proteins: Lower CSF Aβ_1-42 levels and earlier onset of dementia in PD.

Abstract

To evaluate whether genetic variants in β-amyloid (Aβ) clearance proteins are associated with CSF levels of Aβ_1-42 on a biological level and the onset of dementia on a clinical level in Parkinson disease (PD). We analyzed genetic variants known to be involved in Aβ clearance in a PD group comprising 456 patients, 103 of them with dementia. Single nucleotide polymorphisms in the genes <i>APOE</i>, cystatin C (<i>CST</i>), and membrane metalloendopeptidase (<i>MME</i>) were evaluated in relation to demographic variables, clinical phenotypes, and CSF Aβ_1-42 levels using a cross-sectional approach. Risk variants in the genes <i>APOE</i> and <i>CST</i> were associated with lower CSF Aβ_1-42 levels. Clinically, patients with 2 risk alleles in <i>CST</i> tended to show a shorter interval from age at onset of PD to age at onset of dementia. This study suggests that genetic variants associated with Aβ clearance are involved in the pathogenesis of dementia in PD and possibly influence the onset of dementia.