ABSTRACT
BACKGROUND: Multiple genes have been provisionally associated with Alzheimer's disease, including the coding polymorphisms in exons 8 and 13 in the low density lipoprotein receptor gene (LDLR), situated on chromosome 19p13.2. METHODS: The sample groups consisted of 180 AD patients and 141 control spouses. We carried out genotyping of LDLR8 and LDLR13. RESULTS: The LDLR8 GG genotype was common, found in 84% of the unaffected control subjects and 91% of the AD patients in our study. There was a ninefold elevation in risk associated with GG:CC versus A- and T- among APOE4+ subjects when compared with APOE4- subjects (odds ratio 9.3; 95% confidence interval 1.8 to 48.2). With the additional information on LDLR polymorphism, we defined an overall 12 fold elevation in risk for APOE4 in combination with LDLR GG:CC (11.9; 2.8 to 50.0; Fisher's exact test, p = 0.0002; standard power 0.999), compared with other subjects lacking all three of these polymorphisms. CONCLUSION: These results imply a functional interaction between ApoE and LDL receptor proteins that determines risk for Alzheimer's disease.
Subject(s)
Alzheimer Disease/genetics , Apolipoproteins E/genetics , Polymorphism, Genetic , Receptors, LDL/genetics , Aged , Aged, 80 and over , Apolipoprotein E4 , Female , Genetic Predisposition to Disease , Genotype , Humans , Male , Middle Aged , Protein Isoforms/geneticsABSTRACT
Cystatin C, a protease inhibitor with widespread distribution, is upregulated in response to injury. Levels are elevated in the brains of patients with Alzheimer disease (AD). We compared frequencies for the CST 3 exon 1 polymorphism in patients with AD and controls. A proportional odds model indicated that the CST 3 A and APOE4 combination carried a high risk: a 14-fold elevation for men and 16-fold for women. These risks apply to risk at ages older than 64 years and to a shift in onset to ages younger than 65 years.
