ABSTRACT
Codon 129 polymorphism of the prion protein gene represents a major genetic risk factor for Creutzfeldt-Jakob disease (CJD). Both CJD and Alzheimer's disease (AD) are brain amyloidoses and it would be possible that codon 129 polymorphism plays a role in the susceptibility to AD. In order to investigate this polymorphism in AD the distribution of polymorphic codon 129 of the PRNP gene in 194 probable AD and 124 controls selected in Italy and 109 neuropathologically verified AD and 58 matched controls recruited in the USA was studied. No significant association was found for the PRNP polymorphism in AD compared to controls either in Probable or in Definite AD series even after stratification for APOE polymorphism. This study does not support a role of PRNP polymorphism as a susceptibility factor for AD.
Subject(s)
Alzheimer Disease/genetics , Codon , Polymorphism, Genetic , Prions/genetics , Aged , Aged, 80 and over , Apolipoproteins E/genetics , Female , Genetic Predisposition to Disease , Humans , Italy , Male , Middle Aged , Prion Proteins , United StatesABSTRACT
The human apoE gene (APOE, GenBank accession AF261279) shows a common polymorphism, with the three epsilon2, epsilon3 and epsilon4 alleles resulting from the haplotypes of two C-->T SNPs. However, whereas the three common T-T, T-C and C-C haplotypes corresponding to the epsilon2, epsilon3 and epsilon4 alleles are well known, the last C-T haplotype (GenBank accession AY077451), encoding a fourth apoE allele, has rarely been reported. We detected this fourth allele in a Caucasian patient with motor neuron disease (MND). According to the literature we refer to this allele as epsilon3r. Although several explanations may be proposed for its formation, the existence of this fourth allele is consistent with the evolutionary hypothesis generally accepted for the apoE alleles. The rarity and physiological role of epsilon3r remains to be explained, and requires further investigation.
