title: Genetic cross-interaction between APOE and PRNP in sporadic Alzheimer's and Creutzfeldt-Jakob diseases.
abstract: Alzheimer's disease (AD) and Creutzfeldt-Jakob disease (CJD) represent two distinct clinical entities belonging to a wider group, generically named as conformational disorders that share common pathophysiologic mechanisms. It is well-established that the APOE ε4 allele and homozygosity at polymorphic codon 129 in the PRNP gene are the major genetic risk factors for AD and human prion diseases, respectively. However, the roles of PRNP in AD, and APOE in CJD are controversial. In this work, we investigated for the first time, APOE and PRNP genotypes simultaneously in 474 AD and 175 sporadic CJD (sCJD) patients compared to a common control population of 335 subjects. Differences in genotype distribution between patients and control subjects were studied by logistic regression analysis using age and gender as covariates. The effect size of risk association and synergy factors were calculated using the logistic odds ratio estimates. Our data confirmed that the presence of APOE ε4 allele is associated with a higher risk of developing AD, while homozygosity at PRNP gene constitutes a risk for sCJD. Opposite, we found no association for PRNP with AD, nor for APOE with sCJD. Interestingly, when AD and sCJD patients were stratified according to their respective main risk genes (APOE for AD, and PRNP for sCJD), we found statistically significant associations for the other gene in those strata at higher previous risk. Synergy factor analysis showed a synergistic age-dependent interaction between APOE and PRNP in both AD (SF = 3.59, p = 0.027), and sCJD (SF = 7.26, p = 0.005). We propose that this statistical epistasis can partially explain divergent data from different association studies. Moreover, these results suggest that the genetic interaction between APOE and PRNP may have a biological correlate that is indicative of shared neurodegenerative pathways involved in AD and sCJD.
authors.affiliation: Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain.
authors.forename: Olga
authors.initials: O
authors.lastname: Calero
authors.forename: María J
authors.initials: MJ
authors.lastname: Bullido
authors.forename: Jordi
authors.initials: J
authors.lastname: Clarimón
authors.forename: Ana
authors.initials: A
authors.lastname: Frank-García
authors.forename: Pablo
authors.initials: P
authors.lastname: Martínez-Martín
authors.forename: Alberto
authors.initials: A
authors.lastname: Lleó
authors.forename: María Jesús
authors.initials: MJ
authors.lastname: Rey
authors.forename: Alberto
authors.initials: A
authors.lastname: Rábano
authors.forename: Rafael
authors.initials: R
authors.lastname: Blesa
authors.forename: Teresa
authors.initials: T
authors.lastname: Gómez-Isla
authors.forename: Fernando
authors.initials: F
authors.lastname: Valdivieso
authors.forename: Jesús
authors.initials: J
authors.lastname: de Pedro-Cuesta
authors.forename: Isidro
authors.initials: I
authors.lastname: Ferrer
authors.forename: Miguel
authors.initials: M
authors.lastname: Calero
mesh_terms: D000368:Aged; D000544:Alzheimer Disease / Q000235:genetics*; D001057:Apolipoproteins E / Q000235:genetics*; D016022:Case-Control Studies; D003062:Codon / Q000235:genetics; D007562:Creutzfeldt-Jakob Syndrome / Q000235:genetics*; D005260:Female; D005787:Gene Frequency; D005838:Genotype; D006801:Humans; D008297:Male; D011110:Polymorphism, Genetic / Q000235:genetics; D000072002:Prion Proteins; D011328:Prions / Q000235:genetics*
chemical_list: D001057:Apolipoproteins E; D003062:Codon; C512656:PRNP protein, human; D000072002:Prion Proteins; D011328:Prions