Spinocerebellar ataxias are rare, progressive neurodegenerative disorders. By impairing gait, balance, coordination, speech and fine motor skills, they severely affect patients’ quality of life and independence at middle age1. Ataxias can also significantly shorten their life expectancy. While ataxia is a general term that encompasses many different conditions, some forms have a genetic origin.
Spinocerebellar ataxias: a group of inherited disorders
Spinocerebellar ataxias are a group of autosomal dominant genetic disorders. Among the more than 50 identified spinocerebellar ataxias2 types 3 (SCA 3) and 2 (SCA 2) rank among the most common worldwide. In both spinocerebellar ataxia types 3 and 2, genetic mutations damage the nerve cells responsible for transmitting signals to and from a part of the brain called cerebellum or its connections. While the cerebellum does not initiate movement, it ensures movements are accurate and coordinated and aids in their timing and rhythm. Also, it maintains balance. These genetic defects are responsible for disrupting the coordinated transmission of nerve fiber signals to and from the brain.
“Spinocerebellar ataxia types 3 and 2 are inherited neurodegenerative disorders. The abnormal gene responsible for them is passed from generation to generation by family members who carry it. This familial background can raise challenging questions3: should I undergo genetic testing to determine whether I carry the mutation even though no curative treatment currently exists? What would a positive result mean for my future? If I choose to take that step, where can I find appropriate medical support? How quickly does such a process go?”
Key figures about spinocerebellar ataxia types 3 and 2
50%
Each child of a person with SCA 3 or SCA 2 has a 50 percent risk of inheriting the gene that causes it4. Since the gene is dominant, if it is passed to the child from one parent, the child will develop the disease.
1 to 5 sur 100,000
Spinocerebellar ataxias affect 1 to 5 individuals per 100,000 people worldwide5.
Men and women are affected equally by autosomal dominant ataxias such as spinocerebellar ataxia types 3 and 26.
Patients experience a wide range of symptoms, from incoordination to tremors
Ataxia causes damage to the cerebellum, which is the part of the brain that is responsible for coordinating movement. As a result, symptoms of ataxia are walking and balance difficulties, slurred speech, stumbling, falling, incoordination of hand movements, …
However, in addition to cerebellar ataxia, early symptoms of SCA 3 and SCA 2 often include:
Source: National Ataxia Foundation – What is Ataxia
Patients experience a progressive loss of independence as symptoms develop. In advanced stages of spinocerebellar ataxia types 3 and 2, they struggle with everyday tasks such as getting dressed, showering or even using a phone.
Symptom progression in a patient with spinocerebellar ataxia type 3
What is the prognosis for spinocerebellar ataxia types 3 and 2?
The symptoms of spinocerebellar ataxias 3 and 2 most often begin in mid-adulthood. However, they can also emerge as early as childhood or adolescence or as late as age 70.
The disease typically progresses over one to two decades although disease progression can vary significantly between patients. The majority of patients are in a wheelchair 10 years after the first symptoms occurred.
SCA 3 and SCA 2 are diseases of a family with generational impact. The biggest worry is to pass on or having passed on the disease to the children without a cure.
Beyond treatment: improving the quality of life for patients living with spinocerebellar ataxia types 3 and 2
To date, there is no cure for spinocerebellar ataxia type 3 and 2. As a result, patient care should be comprehensive and multidisciplinary and focus on managing the symptoms of ataxia to preserve the patients’ quality of life and independence. This requires close collaboration between medical specialists like neurologists and allied health professionals, including physiotherapists, occupational therapists or speech therapists
Adapting the patients’ living environment is also absolutely key as the progression of the disease often leads to dependency on assistive devices such as wheelchairs and hospital beds.
Finally, psychosocial support should not be neglected as it is essential to help patients and caregivers cope with the emotional, psychological and social consequences of spinocerebellar ataxia.
“The absence of a curative treatment for spinocerebellar ataxia types 3 and 2 calls for a multidisciplinary approach focused on quality of life, symptom relief, environmental adaptation and psychosocial support for both patients and their families.”
Annette Merdes, R&D Clinical Development Lead, Neurology Therapeutic Area, Servier
About Servier
Servier in neurology: A commitment to addressing major medical needs in rare diseases
At Servier, we focus on creating new medicines that slow down or halt the progression of rare neurological disorders and significantly improve patient quality of life. We are committed to addressing this major unmet medical need in neurology with a particular focus on clusters within rare neurological diseases, including rare movement disorders. Theyare an expansive and diverse group of uncommon neurological conditions, often genetic or inherited, that typically begin in childhood or early adulthood. They are marked by abnormal involuntary movements and are frequently progressive and disabling with limited treatment options9. Examples: Friedreich’s ataxia and spinocerebellar ataxia.
[1] Publication – revue ASC, y compris l’âge au moment de l’apparition, Spinocerebellar ataxia – PubMed – https://pubmed.ncbi.nlm.nih.gov/30975995/
[2] de Almeida Franzoi AE, da Silva GF, de Souza Somensi E, de Moura Campos MH, Wollmann GM, Fustes OJH, Marques GL, Teive HAG. Polyneuropathy in Patients with Spinocerebellar Ataxias Types 2, 3, and 10: A Systematic Review. Cerebellum. 2024 Dec;23(6):2593-2606. doi: 10.1007/s12311-024-01730-w. Epub 2024 Aug 29. PMID: 39198325 – https://pubmed.ncbi.nlm.nih.gov/39198325/ – consulté le 09.07.2025
[3] 2025 Rensink_mutation carrier’s preferences regarding onset progression predictions qual interview_Human Genetics.pdf – https://serviergroup-my.sharepoint.com/:b:/r/personal/veronique_crutel_servier_com/Documents/Bureau/SCA/Disease/patient%20pathway%20-burden%20-%20preference/2025%20Rensink_mutation%20carrier%27s%20preferences%20regarding%20onset%20progression%20predictions%20qual%20interview_Human%20Genetics.pdf?csf=1&web=1&e=hjavko
[4] National Ataxia Foundation – Spinocerebellar Ataxia Type 2 (SCA2) – https://www.ataxia.org/wp-content/uploads/2019/04/SCA2.pdf et Spinocerebellar Ataxia Type 3 (SCA3) Machado-Joseph Disease (MJD) – https://www.ataxia.org/wp-content/uploads/2019/04/SCA3-MJD.pdf – consultés le 08.07.2025
[5] Paris Brain Institute – Spinocerebellar ataxias: a widely underestimated diversity – https://parisbraininstitute.org/news/spinocerebellar-ataxias-widely-underestimated-diversity -consulté le 09.07.2025
[6] National Ataxia Foundation – What is Ataxia – https://www.ataxia.org/what-is-ataxia/- consulté le 09.07.25
[7] Ashizawa, 2018 Nat Reviews ; GPH, nombre estimé de patients recevant un diagnostic de SCA3 en 2047
[8] Spinocerebellar Ataxia – Epidemiology – Mature Markets Data | Clarivate – https://clarivate.com/life-sciences-healthcare/report/epidcg0167-biopharma-spinocerebellar-ataxia-epidemiology-mature-markets-data/- consulté en 2025
[9] www.movementdisorders.org