If My Mother Has Alzheimer’s Disease, Will I Get It?

[Anonymous]

If My Mother Has Alzheimer’s Disease, Will I Get It?

[Genetic Counselor]

Having a mother with Alzheimer’s disease does not mean that you will definitely develop the condition. However, your risk may be higher than that of someone without an affected first-degree relative.

The actual risk depends on several factors, including the mother’s age at diagnosis, the number of affected relatives and whether a disease-causing genetic variant is present.

Late-Onset Alzheimer’s Disease

Late-onset Alzheimer’s disease generally develops after 65 years of age. It is the most common form and usually results from a combination of ageing, genetic susceptibility, environmental influences and lifestyle factors.

For example, imagine a 75-year-old woman diagnosed with Alzheimer’s disease. She has two children who are currently healthy.

Her children do not automatically inherit Alzheimer’s disease. They may have a somewhat increased risk because their mother is affected, but this does not mean that they will develop the condition.

The APOE gene is an important genetic susceptibility factor.

It has three common alleles:

APOE ε2: Generally associated with a lower risk.

APOE ε3: The most common allele.

APOE ε4: Associated with an increased risk of Alzheimer’s disease.

Having one ε4 allele increases susceptibility, while having two copies generally increases the risk further.

Importantly, APOE ε4 is a risk allele, not a disease-causing mutation. It cannot reliably predict whether an individual will develop Alzheimer’s disease or when symptoms will begin.

Early-Onset Familial Alzheimer’s Disease

The situation is different when a parent develops Alzheimer’s disease at a relatively young age, particularly before 65, and several relatives across generations are also affected.

Rare pathogenic variants in APP, PSEN1 and PSEN2 can cause autosomal dominant familial Alzheimer’s disease.

If a parent carries a confirmed pathogenic variant in one of these genes, each biological child has a 50% chance of inheriting that variant.

This is called autosomal dominant inheritance.

When Should You Consider Genetic Counselling?

Genetic counselling is particularly important when:

The affected parent developed symptoms before 65.

Multiple relatives have Alzheimer’s disease or unexplained dementia.

Several generations on the same side of the family are affected.

A known pathogenic variant has been identified in the family.

Ideally, genetic testing should begin with the affected parent. If a pathogenic variant is identified, adult biological relatives can consider targeted predictive testing after appropriate counselling.

[Author]

Posts