Alzheimer’s disease is a neurodegenerative disorder affecting memory, cognitive and non-cognitive functions. Studies show that most cases of Alzheimer’s disease pertains to people who are 60 years of age or older; meanwhile, 80% of these cases are due to genetics. The risk of one having Alzheimer’s disease varies with their age and ethnicity. That being said, some elders are obtaining this disease in very late life, nearing their 90’s.
The gene that is usually responsible for Alzheimer ’s disease (AD) is the Apolipoprotein E (APOE gene) which gets its name from encoding for the protein Apolipoprotein. It is on chromosome 19 and has three main alleles on the gene that seem to be responsible for this disease. They are: ε2, containing cysteine at position 112 and arginine at position 158 of the gene, ε3 containing cysteine at both 112 and 158 positions, and ε4 containing arginine at both 112 and 158 positions of the gene. The APOE ε4 allele is the disease’s most prevalent allele. The APOE ε4 allele is the disease’s most prevalent allele. The function of this gene is to regulate cholesterol and triglyceride metabolisms. This shows it is not only coincidental that high cholesterol and diabetes lead to late-onset Alzheimer’s. The APOE ε4 allele was tested and discovered to be so dangerous in 1993. Since, many more studies have been completed on this allele and it has been known to be the main cause of Alzheimer’s disease.
Once all the human genotype was known after using the Human Genome Project, a microarray system used to study over 80 percent of the Caucasian genome for association signals called the 500K GeneChip from Affymetrix was created. This microarray kit was used to confirm that using high-density single nucleotide polymerase genotyping will identify a gene’s loci much faster than the old method of using microsatellite markers. When the genome was initially scanned, microsatellite markers did not show presence of the locus on chromosome 19 where as high density SNP polymerase genotyping did. Oddly enough, the ε4 allele is not yet in the human genotyping system. Once the allele is added it will be very beneficial to use the 500K GeneChip to support how dangerous this allele is.
A study was completed using the brain tissue of a sample of 1086 people all above the age of 65 years (brain tissue samples). 502, 627 SNP’s were used from the DNA of the brain tissues extracted. 664 of the people, referred to as patients were diagnosed with Alzheimer’s; the remaining 422 controlled people did not express any symptoms of the disease. Further testing’s were completed on the individuals and found information on the neurotic plaque density which was useful for the Consortium to Establish a Registry for Alzheimer’s disease protocol. 18% were patients and 16% were controls in the experiment. Braak and Braak Staging were also used and this was when the distribution of neurofibrillary tangles was discovered. Here 59% percent were...