*Patient portrayal

Knowing is strength.

Learn more about ALS.

For many, ALS appears without warning and seemingly without reason. But for some, ALS may be caused by specific genes in the body’s cells that no longer work correctly.1

Welcome to insideALS

At insideALS.eu, you will find resources about genetic ALS that have been developed by Biogen in consultation with ALS specialists and patient advocacy groups for people living with ALS and caregivers.

*Patient portrayal

Not all ALS is the same.

ALS is a rare, progressive, and fatal disease that impacts nerve cells in the brain and spinal cord, leading to loss of muscle function throughout the body.2 It most commonly affects people between the ages of 40 and 70, with a typical age of diagnosis being 55.2,3 While ALS is a complex disease without a cure, ongoing research could have important implications for earlier diagnosis and appropriate care.1,3



Usual age range of diagnosis3

The impact of ALS.

ALS is a rare disease that affects about 1 in 52,000 people worldwide.4 While these numbers may represent a relatively small proportion of the world’s population, the impact of ALS on individuals and families is anything but small.5

ALS can affect people in different ways depending upon the location of the nerve cells that are impacted, but early signs and symptoms often include weakness in the limbs, muscle cramping and twitching, labored speech, and difficulty swallowing.2,6 These symptoms spread and worsen as ALS progresses, eventually resulting in paralysis and respiratory failure.2

ALS disease management today.

While there is no cure for ALS, there are treatments available that can help relieve symptoms and improve quality of life. Various medical devices offer assistance with breathing, mobility, and communication, while counselling services can provide emotional and psychological support. When provided by specialists in an ALS center, treatments like these may lead to increased survival and fewer hospitalizations for people living with ALS.7


Unfortunately, challenges in reaching an ALS diagnosis can lead to delays in treatment. Early ALS symptoms are often difficult to identify, especially by doctors who don’t typically treat the disease, and this can result in late referrals to specialists.6,7 Early diagnosis can help people living with ALS avoid lengthy and expensive tours of the healthcare system, start treatment sooner, and plan for the future.7,8


In recent years, researchers have expanded their understanding of ALS as they’ve searched for new approaches to treatment.

Understanding “genetic ALS” and the role it plays.

Historically, people with ALS were thought to be in one of two groups: those with familial ALS (fALS), which is inherited from a family member, and those with sporadic ALS (sALS), which occurs without a known family history of the disease.9 Approximately 5-10% of people with ALS are thought to have fALS, while sALS accounts for about 90-95% of all ALS cases.10,11


Recent scientific discoveries have identified more than 25 genes linked to ALS.3 Researchers hope that the identification of these genes can lead to earlier diagnosis and therapeutic intervention, both of which are important for people with ALS.1,6 A number of these genes have been found in people with both fALS and sALS.3 This means that even if a person has no known family history of ALS, a genetic component may still be involved. Cases that have a genetic component—across both fALS and sALS—are referred to as “genetic ALS.”

A closer look at the most common genes associated with ALS.

The most common genes associated with ALS are SOD1 and C9orf72, which are described in more detail below.3 By learning more about the genes associated with ALS, the ALS community hopes to learn more about the disease and how it may progress.10


The first gene that was discovered to be associated with ALS was SOD1.1,12 In people with SOD1-ALS, the SOD1 gene has undergone a change, or mutation, which results in damage to nerves in the brain and spinal cord that control muscle movement.10,13


SOD1 gene mutation accounts for just 2% of all ALS cases. Among all ALS patients with a genetic component, approximately 20% are associated with a mutation of the SOD1 gene. For half of the patients with SOD1 ALS there is no known family history of ALS.4,10,14,15

2 in 10


~1 in 2



C9orf72 is short for “chromosome 9 open reading frame 72,” and is the most common ALS-linked gene mutation, affecting approximately 33% of familial ALS patients and 5% of sporadic ALS patients.17 As there are many more sporadic ALS patients than familial ALS patients, it is thought that there may be more C9orf72 ALS patients who do not have a known family history of ALS.4,10,17

*Patient portrayal

Knowing is clarity.

If you are a person living with ALS or a caregiver, it could be important to know if a genetic form of ALS may be affecting you or your loved one.

Genetic testing for all people living with ALS—those with a known family history of ALS and those that do not have a known family history of ALS—may help in understanding the condition better and could assist with long-term life choices.1

Important facts about genetic ALS.

Genetic testing across patients with seemingly sporadic ALS.

Total estimated ALS population: 222,8014
Est. population: 200,5204,10
~90-95% of total4,10
Est. population: 22,2804,10
~5%-10% of total4,10
~10% of sALS patients have a known genetic component
Est. population: 20,05218
~70% of fALS patients have a known genetic component
Est. population: 15,59618
~90-95% of total4,10
Est. population: 200,5204,10
~10% of sALS patients have a known genetic component
Est. population: 20,05218
~5%-10% of total4,10
Est. population: 22,280
~70% of fALS patients have a known genetic component
Est. population: 15,59618
Patient estimates based on 222,801 patients worldwide (2015). Worldwide ALS patient population estimates based on representative country incidence rates applied to their continent's population, as well as a pooled analysis of Europe.4

It is important to stay up to date with genetic ALS information.

The science of genetic ALS is changing, and ALS specialists and researchers are learning more about ALS-associated genes. There are a growing number of clinical trials focused on genetic ALS (https://www.clinicaltrials.gov). By staying up to date with information about genetic ALS, you and your loved ones can be better equipped to talk with your physician about your condition.


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3. Nguyen HP, Van Broeckhoven C, van der Zee J. ALS genes in the genomic era and their implications for FTD. Trends Genet. 2018;34(6):404-423.

4. Arthur KC, Calvo A, Price TR, Geiger JT, Chiò A, Traynor BJ. Projected increase in amyotrophic lateral sclerosis from 2015 to 2040. Nat Commun. 2016;7:12408.

5. Gladman M, Zinman L. The economic impact of amyotrophic lateral sclerosis: a systematic review. Expert Rev Pharmacoecon Outcomes Res. 2015;15(3):439-450.

6. Kiernan MC, Vucic S, Cheah BC, et al. Amyotrophic lateral sclerosis. Lancet. 2011;377(9769):942-955.

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8. Andersen PM, Abrahams S, Borasio GD, et al; for EFNS Task Force on Diagnosis and Management of Amyotrophic Lateral Sclerosis. EFNS guidelines on the clinical management of amyotrophic lateral sclerosis (MALS) – revised report of an EFNS task force. Eur J Neurol. 2012;19(3):360-375.

9. Hartzfeld D. ALS fact sheet. FYI: Familial Amyotrophic Lateral Sclerosis (FALS) and Genetic Testing. [online] June 2020 [cited 2021 Jun 8]. Available from: URL: https://www.als.org/navigating-als/resources/familial-amyotrophic-lateral-sclerosis-fals-and-genetic.

10. Zarei S, Carr K, Reiley L, et al. A comprehensive review of amyotrophic lateral sclerosis. Surg Neurol Int.2015;6:171.

11. Byrne S, Walsh C, Lynch C, et al. Rate of familial amyotrophic lateral sclerosis: a systemic review and meta-analysis. J Neurol Neurosurg Psychiatry. 2011;82(6):623-627.

12. Rosen DR. Mutations in Cu/Zn superoxide dismutase gene are associated with familial amyotrophic lateral sclerosis. Nature. 1993;364(6435):362.

13. Robberecht W, Philips T.The changing scene of amyotrophic lateral sclerosis. Nat Rev Neurosci. 2013;14(4):248-264.

14. Chiò A, Mazzini L, D’Alfonso S, et al. The multistep hypothesis of ALS revisited. The role of genetic mutations. Neurol. 2018;19:e635-e642.

15. Lattante S, Marangi G, Doronzio PN, et al. High-Throughput Genetic Testing in ALS: The Challenging Path of Variant Classification Considering the ACMG Guidelines. Genes.2020;11:1123.

16. Bunton-Stasyshyn RK, Saccon RA, Fratta P, et al. SOD1 Function and Its Implications for Amyotrophic Lateral Sclerosis Pathology: New and Renascent Themes. Neuroscientist. 2015;21(5):519-529.

17. Zou ZY, Zhou ZR, Che CH, et al. Genetic epidemiology of amyotrophic lateral sclerosis: a systematic review and meta-analysis. J Neurol Neurosurg Psychiatry. 2017;88(7):540-549.

18. Volk E, Weishaupt JH, Andersen PM, et al. Current knowledge, and recent insights into the genetic basis of amyotrophic lateral sclerosis. Medgen. 2018;30:252-258.