How APOE Genotyping Can Assess Your Susceptibility for Alzheimer’s Disease

Alzheimer's disease is the most common cause of dementia worldwide, affecting millions in the United States. Medical science continues to research the causes and best treatment options for this debilitating condition.

Miami-based neurologist Dr. Andrew Lerman is an avid researcher and proponent of developing new and improved treatments that are science-backed and clinically proven for conditions like Alzheimer’s.

Read what Dr. Lerman and our team at Gables Neurology in Miami, Florida, say about the pros and cons of APOE genotyping and its significance in identifying your risk of Alzheimer’s disease. 

What is APOE?

Genes control cellular function. Some, for instance, determine whether your eyes are blue or brown or your hair is curly or straight. Other genes may help protect against certain diseases — or not. 

For instance, BRCA1 and BRCA2 genes typically protect against tumor growth. On the other hand, specific mutations in the BRCA genes may indicate an increased risk of developing breast or ovarian cancer.

Certain genes are linked to Alzheimer’s disease, including the APOE (apolipoprotein E) gene. There are three main variants (alleles) of the APOE gene (e2, e3, and e4).

Everyone inherits two copies of the gene (one from each parent), creating several possible combinations that can increase your risk of developing late-onset Alzheimer’s — or not.

Note that early-onset Alzheimer’s (appearing between ages 30-60) is linked to different genes, namely amyloid precursor protein (APP), presenilin 1 (PSEN1), and presenilin 2 (PSEN2). 

How is APOE linked to Alzheimer's disease?

The connection between the APOE gene and late-onset Alzheimer’s varies. For instance:

APOE2

The e2 variant may have a protective effect against Alzheimer's, meaning those with this allele might have a lower risk of developing the disease. Unfortunately, this is the least common variant.

APOE3

This is the most common variant but doesn’t seem to affect your risk of Alzheimer’s one way or the other.

APOE4

Among the three main alleles, APOE4 is particularly interesting because it has been associated with an increased risk of developing late-onset Alzheimer's disease.

Inheriting one APOE4 gene from one of your parents may double your risk of Alzheimer’s. Inheriting two (one from each parent) further increases your risk. 

Should I have APOE genotyping if I’m worried about Alzheimer’s?

Overall, APOE genotyping offers a glimpse into an individual's genetic predisposition toward Alzheimer's disease. It's a piece of the larger puzzle of factors that can influence the onset of this condition, including other gene types, lifestyle habits, and environmental concerns.

At Gables Neurology, Dr. Lerman recommends testing, preventive measures, and treatments for Alzheimer’s based on your individual needs. Regarding APOE genotyping, he cautions that while results may predict Alzheimer's, they’re certainly not determinative.

Having the APOE4 allele may increase your risk, but it doesn’t guarantee you’ll develop Alzheimer’s. And not having the variant doesn’t guarantee you won’t develop the condition.

If we consider prescribing anti-amyloid therapies for Alzheimer’s treatment, APOE genotyping can help indicate whether you’re vulnerable to adverse side effects. Thus, you may benefit from testing.

On the other hand, early-onset Alzheimer’s appears closely linked to genetic factors. Thus, you may benefit from genotyping for other markers (APP, PSEN1, PSEN2) if you’re experiencing concerning symptoms or have a family history of Alzheimer’s before age 50.

For expert care, including information about the latest innovations in Alzheimer’s diagnosis and treatment, schedule an evaluation with Dr. Lerman at Gables Neurology today.