Familial ALS (fALS) and sporadic ALS (sALS)

Historically, people with ALS were thought to be in one of two groups: those with familial ALS (fALS) and those with sporadic ALS (sALS).

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What is ALS? / Familial ALS and sporadic ALS

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Not all ALS is the same

Sporadic ALS

When someone is diagnosed with sporadic ALS (sALS), it means that they have no known family history of the disease. The majority of people with ALS are classified as sporadic. However, many of these patients may be unaware of a family history of the disease.

Familial ALS

The second type of ALS someone may be diagnosed with is familial ALS (fALS). It is defined by a known family history of the disease, where one or more relation has a confirmed diagnosis of ALS.

Infographic about the ALS types: sALS covers 90-95% of total and fALS covers 5-10%

In people with fALS or sALS, a genetic component may be a contributing factor

While it may seem that ALS would only have a genetic component in people with fALS—since genetic mutations are inherited from one’s parents—this is not the case. When looking at the total ALS population:

The majority (~90%) will be diagnosed with sALS, and of these, ~10% will have a genetic component to their disease
Most of the remaining people in the total ALS population—around 5%-10%—will be diagnosed with familial ALS, and of these, ~70% will have a known genetic component

While genetic mutations are found in a higher percentage of people with fALS, there are actually more people with sALS who are believed to have a genetic component to their disease.

Why is it important to know whether you have a genetic component to your ALS?

Knowing whether you have a genetic component to your ALS may help you to better understand the basis of your condition, allow for more comprehensive healthcare decisions and help inform family planning for future generations. It may also allow for genetic counseling to help you understand what it means to have a genetic mutation.

Potential risks of genetic testing

While the physical risks associated with genetic testing may be minimal, there can be emotional, social, or financial consequences to obtaining a genetic test
The possibility of genetic discrimination in employment, as well as for disability or life insurance, can also be a concern for someone living with ALS

For these reasons, you may be referred to speak with a genetic counselor before, during, and after receiving genetic testing results. A genetic counselor can further explain to you in detail the benefits, risks, and limitations of genetic testing.

What is genetic ALS?

Staying up to date with information about genetic ALS could help you and your loved ones communicate more effectively with your doctor about your disease.