What is a gene?

It is well-known that our DNA has the required structure to allow for life to exist. The proteins that make up life’s processes and the concentrations of those proteins are determined by the makeup of our DNA. A portion of the most prominent health complications that people face result from an imbalance of the proteins within their body. When people consider the question, what is a gene? The simple answer is: a gene is a section of DNA that codes for a specific protein or combination of proteins required for proper cell functioning. People have different combinations of genes, and thus, the genetic risk for a particular disease varies from person to person.

What is the most common gene involved in Alzheimer’s Disease?

The APOE gene lies on the 19th chromosome and is responsible for the synthesis of apolipoprotein E. Lipoproteins are composed of protein and lipids (fats) in the body, and are responsible for the transport of cholesterol and lipids through the bloodstream. Here are some things that have been indicated through research conducted on the APOE allele:

• The APOE*4 gene has the greatest currently-known effect on the risk of a person getting Alzheimer’s disease.
• This allele is present in 25-30% of the population
• More than 60% of people with AD have at least one APOE*4 allele.
• The APOE*3 allele is another APOE gene variant, and is not known to affect the risk of receiving an Alzheimer’s Disease diagnosis.
• The presence of the APOE*2 allele seems to be protective from an Alzheimer’s diagnosis.
• The number of APOE*4 alleles that a person has, their gender, and their age all contribute to their overall risk of getting AD.

What is a gene risk-score calculation?

At this point in the genetic research that has been conducted on Alzheimer’s Disease, a comprehensive list of all the genetic variants associated with the disease has not been identified. A study on the APP gene (which codes for the amyloid precursor protein that can be found in synapses between neurons) showed that people with Trisomy 21 have more amyloid beta plaques in their brains, and thus show the progression of AD early in life. There are many other genes that affect the presence of Alzheimer’s Disease, and they can all be used together to produce an overall polygenic risk score calculation.
Recent research conducted by our partners at ADx healthcare has revealed 26 genetic variants associated with the presence of Alzheimer’s disease. Some of these variants are associated with increased risk for the disease while others protective for disease risk. These variants have been analyzed to create a Geno Risk score which provides patients with a lifetime risk and an age-specific risk based on the current absence of the disease. This test will be available through Helix Genetics and ADx Healthcare in the coming months. This will provide valuable information alongside the other tests that are currently available (with many more to come) through Brain Stride.