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Ataxia-Telangiectasia

(A-T; Louis-Bar Syndrome) Compact Guide 2024​

Written by

Dr. Cinthia Briseño

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Written according to scientific standards
Last updated on 05th of August 2024
Reading time approx. 9 minutes

Ataxia-Telangiectasia: The Rare Hereditary Disease at a Glance

Ataxia-Telangiectasia, also known as Louis-Bar syndrome or A-T, is a very rare hereditary disease that affects both girls and boys starting in early childhood. It usually first becomes noticeable between the ages of one and four years through ataxias.1 Ataxia refers to difficulties with coordinated movement, making activities such as walking or balancing increasingly challenging for affected children. Unintentional movements, such as jerking, are also typical for A-T. Over time, the disability progresses and children may become dependent on a wheelchair, usually at 10 to 12 years of age. However, the severity of A-T can vary from child to child. In addition to issues with movement coordination, there are other symptoms associated with A-T, such as eye movement disorders and visible dilation of blood vessels (telangiectasia) in the eyes or auricles. Frequent respiratory infections due to a weakened immune system are also typical signs. People with A-T have a significantly increased risk of developing a malignant tumor disease such as leukemia or lymphoma. It is estimated that A-T occurs in 1 in 40,000 to 100,000 newborns worldwide2. Mutations in a specific gene are the cause; therefore, A-T cannot be cured. So far, treatment options only aim to alleviate the symptoms or prevent them as best as possible. The emphasis lies on physiotherapy, occupational therapy, speech therapy, vaccinations, good cancer prevention, and rapid treatment of infections. There are currently no pharmacological therapies available to cure A-T. Nevertheless, researchers are developing new and innovative approaches with drugs that could be approved for A-T in the future. Is your child suspected of having A-T or already diagnosed with A-T? This guide aims to encourage you: It brings together a wealth of knowledge and practical information for you. It may help you to understand Ataxia-Telangiectasia better – and can thus offer you support in dealing with your child’s rare hereditary disease. If your child is affected by A-T, you can also help researchers now by sharing your experiences dealing with your child’s condition in an international A-T survey. By doing so, you are contributing to improving the treatment options for A-T!

Contents

1. Background Knowledge

2. Symptoms and Progression

3. Diagnosis

4. Treatment and care

5. Contact points

6. New treatments

1

Background Knowledge

The Most Important Facts About Ataxia-Telangiectasia

Symptoms may begin in early childhood with uncoordinated movements, a wobbly gait, and difficulty standing upright. In some cases, these symptoms are caused by a hereditary disease which, although very rare, has serious consequences: Ataxia-Telangiectasia, or A-T for short, also known as Louis-Bar syndrome.

A-T is a neurodegenerative systemic disease. Over time, nerve cells in the brain lose their ability to function, leading to a variety of symptoms, e.g., affected children may no longer be able to walk from around the age of ten, become susceptible to respiratory infections, and have a significantly increased risk of tumor diseases.

Unfortunately, this results in a reduced life expectancy for people with A-T, challenges for those affected, their families, and their social environment. Knowing as much as possible about the disease becomes pivotal in managing A-T. Sound knowledge will help you find the proper support for your child and take measures as early as possible to alleviate symptoms and delay severe consequences.

What is the cause of A-T, and how does the disease develop?

Ataxia-Telangiectasia (A-T) is caused by mutations in a specific gene called ATM. A child can only develop A-T if both parents possess the defective ATM gene in their genome (DNA). This type of heredity is known as autosomal recessive. If both parents are carriers of the defective gene, the following probabilities for a pregnancy arise:

How often does A-T occur?

Around one in a hundred people carry a mutation in the ATM gene 3 without developing the disease. The reason is that if only one of two copies of the ATM gene is defective, the other copy largely compensates. Around one percent of the world’s population has the risk of passing on a defective gene copy. Only if the other parent is also a carrier of the ATM mutation will there be a chance that their child develops Ataxia-Telangiectasia (A-T). A-T is, therefore, one of the very rare hereditary diseases. According to estimates, only around one in 40,000 to 100,000 newborns are affected.1,4

What are the effects of ATM mutations?

Mutations in the ATM gene have a significant impact on the body. The ATM gene provides the blueprint for the essential ATM protein. The ATM protein helps cells recognize and repair DNA damage, i.e., the genetic material, which is a critical process for maintaining the stability and function of our cells.

If both ATM gene copies are defective, the body produces either no ATM protein or only a defective ATM protein. As a result, cells are unable to repair DNA damage. DNA damage gradually accumulates, leading to cell dysfunction or death over time.

Ataxia-Telangiectasia in a Nutshell

A-T is a very rare but severe hereditary disease affecting the nervous and immune systems
A-T is characterized by progressive difficulty in coordinating movements (ataxia) and dilated blood vessels (telangiectasia
A-T is caused by mutations in the ATM gene, which is vital for DNA repair.
A-T leads to an increased susceptibility to recurring respiratory infections and a significantly increased risk of cancers such as leukemia or lymphoma.
A-T is usually diagnosed in early childhood and often leads to a reduced life expectancy.

Nerve cells in the brain are particularly susceptible to the damaging effects of ATM mutations. In the long term, DNA damage leads primarily to the death of cells in the cerebellum. This is the reason why A-T causes ataxia, i.e., uncoordinated movements that progress continuously.

The ATM gene defect also affects cell types that divide frequently. These include cells of the immune system, blood-forming cells or cells in the skin, and mucous membranes. The consequences include a weakened immune system, an increased risk of certain tumor diseases such as leukemia and lymphoma, as well as the development of telangiectasias. Telangiectasias are dilated small blood vessels that are often visible in the whites of the eyes and on the skin.

Is your child affected by Ataxia-Telangiectasia (A-T)?

Then you can now take part in an international survey and tell us about your experiences dealing with this rare hereditary disease. Simply answer a few questions and help us improve treatment options for A-T!

Take part in the A-T Survey now

Symptoms and Progression

The Different Facets of A-T

2
Especially in the early stages, the symptoms of Ataxia-Telangiectasia (A-T) are not always distinct and may be mistaken for other neurological conditions. As a result, it can sometimes take a long time for children with A-T to receive a confirmed diagnosis. To better understand the progression of the disease, researchers at the University of Nottingham, UK, conducted a systematic review of the scientific literature on A-T in 2002 based on all the available publications worldwide since 1946.1 The analysis of A-T cases included in the literature reveals the many facets of the disease and its typical course

Typical features of A-T

Ataxia-Telangiectasia (A-T) usually begins at the age of twelve to 18 months with a wobbly gait. By the age of around ten, most children are no longer able to walk due to the progressive damage to the cerebellum and require a wheelchair.5 From the age of three to four years, complications affecting the immune system and the respiratory tract start occurring as well: Children with A-T are prone to recurring respiratory infections, which lead to a deterioration in lung function. In addition, affected children also develop telangiectasias. These are dilated blood vessels that appear as small red or purple spots on the skin or mucous membrane and are often seen in the conjunctiva of the eyes or on the auricles. However, they can also occur in other organs, such as the bladder. Over time, children affected with A-T develop a variety of other neurological issues. These include, for example
  • Dysarthria, i.e., speech disorders
  • Oculomotor apraxia, i.e., movement disorders of the eyes
  • other neurological disorders that can lead to involuntary, abrupt, or twisted movements and persistent muscle contractions and twisted postures, for example.

While the neurological symptoms can also have other causes, telangiectasias, i.e., dilated blood vessels, are one of the characteristic features of A-T – and are helpful for a reliable diagnosis. They also typically appear at the age of three to four years.

Unfortunately, the severe symptoms of A-T often have serious consequences in the further course of the disease: the average life expectancy for classic A-T is 20 to 30 years. The most common causes of death include infections caused by A-T and the significantly increased risk of certain cancers, including leukemia and lymphoma.

Good to know: Despite the typical characteristics of A-T, the severity of the symptoms can vary significantly from child to child.

The milder form of A-T

Besides the “classic” form of A-T, there is also a milder variant. The key difference lies in how the ATM gene is mutated. Consequently, the ATM protein isn’t completely defective but remains partially functional, leading to milder symptoms and slower disease progression. People with mild A-T often have a longer life expectancy and experience less severe neurological and immunological issues.

Is your child affected by Ataxia-Telangiectasia (A-T)?

Then you can now take part in an international survey and tell us about your experiences dealing with this rare hereditary disease. Simply answer a few questions and help us improve treatment options for A-T!

Take part in the A-T Survey now

Diagnosis

3

The Most Important Examinations for Suspected A-T

Good to know: The earlier an A-T diagnosis is made, the sooner targeted medical interventions can begin. They can alleviate the symptoms and thus improve the child’s quality of life at a young age. Additionally, early treatment can potentially prevent complications and increase life expectancy.

How A-T is Diagnosed

Comprehensive examinations and tests are necessary for a reliable Ataxia-Telangiectasia diagnosis. The first step is a thorough physical examination with various tests to observe the characteristic features of A-T. These include uncoordinated movements (ataxia), unusual eye movements, and visible skin changes such as dilated blood vessels (telangiectasia).

One example is the finger-nose test: The child places their finger on their nose and then touches the doctor’s finger. With this test, the doctor can assess coordination and hand tremors.

Genetic tests are crucial for confirming a suspected case of A-T: A blood sample is taken from the child to identify the mutation in the ATM gene.6
Other examinations and tests for the diagnostic process include:

Blood tests: Elevated levels of alpha-fetoprotein (AFP) and reduced immunoglobulin levels (IgG or IgA) are typical in many A-T patients.
Magnetic resonance imaging (MRI): MRI scans are performed to look for signs of damage or changes in the cerebellum.
Protein assays: The amount of ATM protein in the blood is measured. In around 90 percent of people with A-T, the ATM protein is not detectable in the blood.

Importance of Early diagnosis

Even though A-T is not yet curable, it is important to know that an early and accurate diagnosis might make a decisive contribution to alleviating the symptoms of this rare disease and improving the quality of life of affected children.7,8,9

The problem is that it often takes a very long time to reach a definitive diagnosis. Sometimes, it takes several visits to numerous specialists and several years before it becomes clear that A-T is the cause of the problems.10 For families, this often means great uncertainty and a heavy emotional burden.

In their publication, the scientists from the University of Nottingham in the UK emphasize the need for further research into A-T to better understand the disease and develop targeted treatment options.

Is your child affected by Ataxia-Telangiectasia (A-T)?

Then you can now take part in an international survey and tell us about your experiences dealing with this rare hereditary disease. Simply answer a few questions and help us improve treatment options for A-T!

Take part in the A-T Survey now

Treatment and Care

4

How to Alleviate Symptoms

With the diagnosis of Ataxia-Telangiectasia (A-T), there is finally certainty as to what is behind your child’s symptoms. Over the years, it will be essential to find suitable doctors and other specialists who can provide you and your child with the best possible support in dealing with the condition.

Early diagnosis allows doctors to develop targeted treatment plans that are specifically tailored to your child’s needs.

In the case of Ataxia-Telangiectasia, appropriate therapies, and regular monitoring are aimed at the following:
Support movement coordination.
Strengthen the immune system.
Reduce the risk of serious infections.
Detect cancer at an early stage.

The Most Important Treatment Approaches for A-T

The care of children with A-T requires a multidisciplinary approach.6 This means that various specialties, including neurology, immunology, physiotherapy, and nutritional advice, play an important role in treatment. In detail, various therapeutic approaches can be considered. These include
In the case of Ataxia-Telangiectasia, appropriate therapies, and regular monitoring are aimed at the following:
  • Airway management: Regular exercises such as chest physiotherapy and the use of cough aids help to clear airway secretions and reduce the risk of infections.
  • Cancer monitoring: Due to the increased risk of certain types of cancer, such as leukemia, regular screening examinations need to be carried out so doctors can perform appropriate measures in a timely fashion.
  • Nutrition: If swallowing disorders (dysphagia) occur, feeding via a gastric tube may be necessary to prevent choking and the risk of suffocation.
Good to know: The severity of the symptoms of A-T can vary from child to child. Therefore, no standard treatment exists. Treatment should, thus, always be adapted to the individual needs and symptoms of the child

Is your child affected by Ataxia-Telangiectasia (A-T)?

Then you can now take part in an international survey and tell us about your experiences dealing with this rare hereditary disease. Simply answer a few questions and help us improve treatment options for A-T!

Take part in the A-T Survey now

Contact Points

Where to Find Help and Support

5
An Ataxia-Telangiectasia (A-T) diagnosis is a shock for most families and poses a heavy emotional burden. It becomes crucial to be well informed on the one hand – and to get comprehensive support and help on the other. Here, you will find a list of the most influential organizations and contact points in the USA, UK, and Germany, which offer a wide range of support and information options for parents of children with Ataxia-Telangiectasia. They help to cope with everyday life, provide emotional support, and promote exchange between those affected:

Contact Points in the USA

A-TCP is a leading organization dedicated to the research and support of patients with Ataxia-Telangiectasia. It was founded by parents whose children suffer from A-T.

What They Offer:

  • Research project funding
  • Organization of clinical studies
  • Support and resources for affected families
  • Public relations and awareness-raising
  • Fundraising and community-building events

Website: https://atcp.org

NORD is a patient organization that advocates for people with rare diseases, including Ataxia-Telangiectasia.

What They Offer:

  • Provide information on rare diseases
  • Support in the search for specialized doctors and treatment options
  • Patient support and advice
  • Research funding

Website: https://rarediseases.org

GARD is a program of the National Center for Advancing Translational Sciences (NCATS) that provides comprehensive information on rare and genetic diseases, including Ataxia-Telangiectasia.

What They Offer:

  • Provide information and resources
  • Support in the search for clinical studies
  • Information on diagnosis and treatment options

Website: https://rarediseases.info.nih.gov

Contact Points in the UK

The A-T Society is the UK’s leading charity dedicated to supporting people with Ataxia-Telangiectasia and their families.

What They Offer:

  • Providing information and resources
  • Financial support for affected families
  • Support with medical care
  • Organization of events and conferences
  • Promotion of research

Website: https://atsociety.org.uk

Ataxia UK supports people with all types of ataxias, including Ataxia-Telangiectasia, through information, support, and research.

What They Offer:

  • Information and helpline services
  • Funding and support for research projects
  • Self-help groups and social support
  • Education and awareness-raising

Website: https://www.ataxia.org.uk

Contact is a national charity that supports families with disabled children, including those with rare diseases such as Ataxia-Telangiectasia.

Services offered:

  • Helplines and support services
  • Information on rare diseases and disabilities
  • Financial support and grants
  • Parent forums and networks

Website: https://contact.org.uk

Genetic Alliance UK is an organization that supports people with genetic, rare, and undiscovered diseases, including Ataxia-Telangiectasia.

What They Offer:

  • Information and support services
  • Lobbying and political advocacy
  • Promotion and research funding
  • Networking and community building

Website: https://geneticalliance.org.uk

Rare Disease UK is the national network for people with rare diseases, including Ataxia-Telangiectasia, who are campaigning for improved services and support.

What They Offer:

  • Education and awareness-raising
  • Support with political advocacy
  • Networking of patients and families
  • Promotion of research initiatives

Website: https://geneticalliance.org.uk/campaigns-and-research/rare-disease-uk/

Contact Points in Germany

DHAG provides information and support for all types of ataxias, including Ataxia-Telangiectasia.

What They Offer:

  • Information material and brochures
  • Helpline and support
  • Self-help groups and local meetings
  • Events and seminars

Website: http://www.ataxie.de/

DGM is the largest self-help organization for people with neuromuscular diseases in Germany and offers extensive support for patients and their families.

What They Offer:

  • Information centers and regional contacts
  • Self-help groups and exchange opportunities
  • Support with social law issues
  • Research and support for scientific projects

Website: www.dgm.org

The association is a unique contact point for families affected by Ataxia-Telangiectasia. It offers support and information, organizes meetings, and promotes exchanges between affected families.

What They Offer:

  • Meetings for families and patients
  • Information material
  • Exchange platforms and self-help groups

Local and regional self-help groups provide affected families the opportunity to exchange information directly and support each other. These groups can often be found through larger patient organizations such as Deutsche Ataxie Gesellschaft.

What They Offer:

  • Regular meetings and exchange opportunities
  • Support and counseling with the help of other affected people
  • Joint activities and events

Some specialized clinics and centers in Germany offer specific medical care and advice for children with A-T. Here are some examples: 

Heidelberg University Hospital offers specialized neurological and genetic counseling and has an Ambulanz für Bewegungsstörungen und Ataxien (outpatient practice for movement disorders and ataxias).

You can find a more comprehensive list of centers and clinics on this website.

There are also several certified centers for rare (neurological) diseases (ZSNE / ZNE) throughout Germany, some of which offer comprehensive care, information, and specialized treatment options, including, for example:

  • Berliner Centrum für Seltene Erkrankungen (BCSE) der Berliner Charité
  • ZSNE des Universitätsklinikum Tübingen
  • Zentrum für Seltene Neurologische Erkrankungen Bonn (ZSEB) des Universitätsklinikum Bonn
  • Essener Zentrum für Seltene Erkrankungen (EZSE) des Universitätsklinikum Essen
  • Zentrum für Seltene Erkrankungen Freiburg (FZSE) des Universitätsklinikum Freiburg
  • Zentrum für Seltene Erkrankungen Heidelberg (ZSEHD) des Universitätsklinikum Heidelberg
  • Zentrum für Seltene Erkrankungen München (ZSEM) der LMU München

Is your child affected by Ataxia-Telangiectasia (A-T)?

Then you can now take part in an international survey and tell us about your experiences dealing with this rare hereditary disease. Simply answer a few questions and help us improve treatment options for A-T!

Take part in the A-T Survey now

New Treatments

6

Development of Novel Therapies

There are currently no approved drug therapies for A-T. Nevertheless, various approaches are being developed or are presently being tested in clinical trials.

One example is an innovative treatment with so-called glucocorticoids: They have a strong anti-inflammatory effect and can improve typical neurological symptoms of A-T. However, to avoid the usual side effects of long-term treatment, glucocorticoids are first encapsulated in the patient’s red blood cells. Doctors then inject this “loaded” blood back into the patient. In this way, the active ingredient is released slowly and evenly.11

Another approach researchers are looking into is antisense oligonucleotide therapy or ASO for short. Roughly speaking, this class of drugs aims to correct the faulty production of the ATM protein caused by genetic ATM mutations. This targeted intervention could also help alleviate neurological symptoms of A-T and slow the progression of the disease.12 However, clinical trials with patients have not yet been conducted.

Is your child affected by Ataxia-Telangiectasia? Help researchers now and take part in the international A-T survey

Is your child affected by Ataxia-Telangiectasia? What experiences have you had in dealing with your child’s condition? Simply take part in the international A-T Survey now, answer a few questions, and tell us about your experiences. Your contribution will help improve treatment options for A-T.

Further information

Quality guideline

This article is based on the German guideline for evidence-based health information, “Leitlinie evidenzbasierte Gesundheitsinformation”. 13

Authors

Dr. Cinthia Briseño

Medical review

Dr. Tobias Kruse, Birgit Schouren

Date

05.08.2024

References

All references were accessed in July 2024.

Important note

This article contains general advice and information. It should not be used for self-diagnosis or self-treatment and does not constitute a recommendation for therapy. It does not replace consulting a doctor. For individual questions, please get in touch with your attending doctor.

Is your child affected by Ataxia-Telangiectasia?

What experiences have you had in dealing with your child’s condition? Simply take part in an international survey now, answer a few questions, and tell us about your experiences.
Take part in the A-T Survey now
  1. Petley E et al. PLOS One. 2023;17(3):e0264177.
  2. Rothblum-Oviatt C et al. Orphanet J Rare Dis. 2016;11:159.
  3. Swift M et al. Am J Hum Gen 39: 573-583.
  4. Riboldi GM et al. Ataxia-Telangiectasia [Updated 2024 Mar 6]. In: StatPearls [Internet]. Available from: https://www.ncbi.nlm.nih.gov/books/NBK519542/, accessed 12 July 2024
  5. Petely E et al. PLoS ONE 17(3): e0264177.
  6. National Organization for Rare Disorders. Ataxia Telangiectasia – Symptoms, Causes, Treatment https://rarediseases.org/rare-diseases/ataxia-telangiectasia/, accessed 12 July 2024
  7. Rothblum-Oviatt C et al. Orphanet J Rare Dis. 2016;11:159.
  8. Khan M et al. The Cerebellum 23: 722-756.
  9. Petley E et al. PLOS One. 2023;17(3):e0264177.
  10. Khan M et al. The Cerebellum 23: 722-756.
  11. Zielen S et al., presented at: 2022 AAN Annual Meeting. Abstract 52072
  12. Kim J et al. Nature 619: 828-836
  13. Guideline on evidence-based health information, version 1.0. 2017 https://www.gesundheit.uni-hamburg.de/pdfs/leitlinie-evidenzbasierte-gesundheitsinformation.pdf, accessed 12 July 2024

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