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ALS (amyotrophic lateral sclerosis) is a progressive neurodegenerative disease that attacks motor neurons, weakens voluntary muscles throughout the body, and leads to paralysis.
When a person has no family history of ALS, frontotemporal dementia (FTD), or related conditions, a genetic cause can be found about 10% of the time. The other 90% of ALS cases are considered sporadic, which means there is no known genetic cause. |
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Sporadic ALS
Researchers do not know what causes the majority of ALS cases, but they continue to investigate. Though no direct associations have been established, some researchers suspect that some cases of ALS could be caused by exposure to environmental toxins such as blue-green algae or heavy metals, a virus, or abnormalities and imbalances in certain cells, molecules, or chemicals. Researchers are investigating whether strenuous physical activity and head trauma are risk factors as well. For unknown reasons, U.S. military Veterans are about twice as likely to develop ALS.
Genetic ALS
When there is no clear family history of ALS or related conditions, a genetic cause for ALS can be found about 10% of the time. But when there is a clear family history of ALS, FTD, or related conditions, a genetic cause can be found about 70% of the time.
Our DNA provides instructions for how our body will grow and function over time. We all have many differences, or variants, in our DNA, and most of them don’t impact our health. However, sometimes there can be a difference in the DNA code that can cause a problem in the body. This is called a pathogenic variant, which may also be referred to as a mutation.
Some genetic variants can cause a person to develop or be at risk of developing a disease like ALS. Researchers have now identified variants in over 40 genes that either cause ALS or increase a person’s likelihood of developing ALS. Some of the most common genetic causes of ALS are variants in the genes C9orf72 (C9) and SOD1.
Our DNA provides instructions for how our body will grow and function over time. We all have many differences, or variants, in our DNA, and most of them don’t impact our health. However, sometimes there can be a difference in the DNA code that can cause a problem in the body. This is called a pathogenic variant, which may also be referred to as a mutation.
Some genetic variants can cause a person to develop or be at risk of developing a disease like ALS. Researchers have now identified variants in over 40 genes that either cause ALS or increase a person’s likelihood of developing ALS. Some of the most common genetic causes of ALS are variants in the genes C9orf72 (C9) and SOD1.
Who should get tested for genetic ALS?
Current guidelines state that anyone diagnosed with ALS should be offered genetic testing for at least the most common genetic variants. Deciding whether or not to get tested is a highly individual decision. Read more
Genetic testing for ALS has become more accessible and more affordable in recent years. It can provide helpful information both for people who already have ALS and for family members who want to know whether they might develop ALS in the future.
To learn who may be at risk for genetic ALS, how counseling can be helpful, how testing works, and where you can get tested, visit our ALS Genetic Counseling and Testing page.
To learn who may be at risk for genetic ALS, how counseling can be helpful, how testing works, and where you can get tested, visit our ALS Genetic Counseling and Testing page.
