association between [8390G>A] single nucleotide polymorphism in APOE gene with Alzheimer's and Parkinson disease

ABSTRACT

Genetic susceptibility, is considered to be involved in neurodegenerative diseases such as Alzheimer's disease [AD] and Parkinson's disease [PD]. Despite the fact that many susceptibility genes for AD and PD have been considered, the most probable genetic risk factor which has been taken into consideration is Apolipoprotein E genotype located on chromosome 19q, APOE is the gene widely considered to be a susceptibility gene for neurodegenerative diseases. This study is to investigate the association of APOE polymorphism with AD and PD. In this case control study we examined association of an APOE gene polymorphism [rs121918398] with AD and PD in Iranian population. The study included 100 AD patients, 100 PD patients and 150 healthy volunteers. An informed consent was obtained from all participants. Genomic DNA was extracted from peripheral blood leukocyte. Genotypes were determined by PCR and restriction fragment length polymorphism [RFLP] by Hha1 restriction enzyme. Sequencing of PCR products was carried out by Fazabiotech Company according to Sanger method using ABI 3730XL Capillary Sequencer. Statistical analysis was performed using the MedCalc program. The prevalence of genotype frequencies of the APOE A/A, A/G, G/G were 16%, 34% and 50% in AD subjects, 14%, 32%, 54% in PD patients and in healthy volunteers were 15%, 39% and 96% respectively. Statistical analysis showed no significant difference between genotype frequencies of AD and those of control subjects [P < 0.05]. Moreover, according to statistical analysis, the genotype frequencies of APOE in PD subjects and control group did not significantly differ. This is the very first time that the association of this polymorphism [rs121918398] with AD is being reported nevertheless, there is no evidence that APOE variant is associated with PD. Accordingly, genotype alteration of A8390>G can't be related to AD. So, this polymorphism plays no pathogenic role in the PD and AD patients in Iranian population