Influence of peroxisome proliferator-activated receptor γ gene polymorphism on 24S-hydroxycholesterol levels in Alzheimer's patients

The peroxisome proliferator-activated receptor gamma( PPAR gamma) is a nuclear hormone receptor, that is involved in lipid and glucose metabolism, which both seem to influence the risk of Alzheimer's disease (AD). 24S-Hydroxycholesterol is the major cholesterol elimination product of the brain and plasma and CSF 24S- hydroxycholesterol levels are altered in patients with neurodegenerative diseases. We investigated the effect of the common Pro12Ala variant of the PPAR gamma gene on plasma cholesterol levels and 24S-hydroxycholesterol/ cholesterol ratios in 124 AD patients and 77 healthy controls. Furthermore, the influence of PPAR gamma polymorphism on the risk of AD in 247 AD patients and 324 healthy controls was investigated. We found that PPAR gamma Pro12Ala polymorphism influenced plasma 24S-hydroxycholesterol/ cholesterol ratios in AD patients in that carriers of the Ala allele presented with higher ratios than homozygote carriers of the Pro- allele. PPAR gamma polymorphism did not influence the risk of AD. These results might point to an influence of PPAR gamma Pro12Ala polymorphism on the elimination of 24S- hydroxycholesterol.