Familial ALS

When describing ALS, a distinction is usually made based on whether or not the disease runs in a family. The two types of ALS are: 

Familial ALS – Approximately 5% to 10% of people living with ALS in the U.S. have family members who have also been diagnosed with the disease, making it probable that a genetic mutation has been inherited. About two-thirds of people with familial ALS have mutations in known ALS genes, indicating that more genes likely remain to be discovered. 

Sporadic ALS – This is the most common form of the disease, affecting approximately 90% to 95% of people living with ALS. Individuals with sporadic ALS are the first people in their families known to have the disease. For the majority of people with sporadic ALS, lifestyle, environmental or other risk factors may have contributed to the development of the disease. However, about 10% of people with sporadic ALS have a mutation in a gene that has been linked to ALS. 

ALS is similar whether it is inherited or appears in a person with no family history of the disease, although people with familial ALS often start showing symptoms at earlier ages. Regardless of whether the disease is familial or sporadic, the progression of ALS can vary quite a bit from one person to another. Even within families, family members who have been diagnosed with ALS may have different disease courses. Researchers are trying to understand these differences to learn more about how to slow disease progression and treat ALS more effectively.  

Genetic Testing 

To find out whether ALS has an underlying genetic cause, people living with the disease can get genetic testing. The decision whether to get a genetic test or not is a very personal one. Genetic testing comes with many benefits, but also some risks, and may not be right for you. Click here to learn more about the benefits and risks of genetic testing for people currently living with ALS. 

Learn more about ALS genetics 

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