Ataxia telangiectasia (AT) is an autosomal recessive, multisystem disorder caused by homozygous or compound heterozygous mutations of the ATM (ataxia telangiectasia mutated) gene which codes for a phosphatidylinositol 3-kinase that responds to cellular DNA damage. It is characterized by progressive neurodegeneration particularly in the cerebellum, with ataxia, oculomotor apraxia, dysarthria, dysphagia, dystonia, movement disorder, immunodeficiency, predisposition to various cancers, recurrent sinopulmonary infections, and progeroid symptoms, typically but not always including telangiectasias.
The ATM gene maps to chromosome region 11q22.3 and its protein product is normally expressed in all tissues in the body. Its functions include:
- Response to deoxyribonucleic acid (DNA) damage and coordination of DNA repair, particularly double strand breaks due to ionizing radiation.
- Regulation of cell cycle and apoptosis and telomere maintenance.
- Response to oxidative stress.
- Mitochondrial homeostasis.
- Regulation of cellular protein turnover.1
Epidemiology including risk factors and primary prevention
The incidence is 1 out of 88,000 live births, 2 with a carrier frequency of 1% in the United States .3 The prevalence in the United States is about 1 in 40,000.
Primary prevention via genetic counseling and prenatal diagnosis is possible. Avoiding consanguinity reduces but does not eliminate risks of autosomal recessive diseases. There is a 25% recurrence risk for each child when both parents are carriers.3
Patients with truncating or inactivating mutations (deletions, insertions, nonsense) in the ATM gene have no functioning ATM kinase, which appears to be involved in a surveillance mechanism that, in the presence of DNA damage, will stall progression of the cell cycle. This delay allows the cell to repair the damage. Without ATM kinase, cells can build up somatic mutations, leading to malignant transformation. The defect in nuclear DNA repair in AT also explains the sensitivity of cells to ionizing radiation. 6
Mitochondrial DNA dysfunction may also contribute to AT and affects cerebellar, basal gangliar, and peripheral nerve function, leading to clinical features such as ataxia, neurodegeneration, and premature aging. 4, 6
Missense mutations tend to lead to a milder disease with later, even adult onset and more solid tumor than hematologic malignancy risk. The severity and progression rate vary even within affected families. 4
Both the central and peripheral nervous systems are involved in AT. The thymus usually is hypoplastic, which is consistent with the associated immune deficiency. 6
Disease progression including natural history, disease phases or stages, disease trajectory (clinical features and presentation over time)
The first symptom is usually ataxic gait, seen soon after independent walking is achieved. In rare cases, dystonia may be the presenting symptom. From 0 to 5 years, recurrent sinopulmonary infections in those with immune deficiencies are common. Cerebellar atrophy on MRI may not be seen at this stage and telangiectasia may be minimal or absent.
By 5 to 15 years, increased falling and overt dysmetria are usually present, and oropharyngeal dysphagia, dysarthria, and oculocutaneous telangiectasias first notable in the bulbar conjunctivae usually develop. These can be seen on the face, neck, and other sun-exposed areas starting at 8-10 years. Oculomotor apraxia (irregular saccades with extraocular movement testing) is usually present by 10 years of age. Walker and wheelchair use, supplemental tube feedings, and academic modifications start to become necessary.
During the adolescent years, ataxia worsens and is accompanied by extrapyramidal symptoms including choreoathetosis, dystonia, tremor, reduced facial expression, bradykinesis, hyperkinesis, and sometimes spasticity. Acquired strabismus may be seen and aspiration is increasingly common. Cognitive impairment is frequently present at the end of the first decade of life, and may become more widespread and severe in the later stages.7, 8 Lymphoblastic leukemia and lymphoma are the most common malignancies at this stage.
Beyond 15 years of age and into the third decade, there are also progressive central nervous system vascular abnormalities and the risks of solid tumors increase. Insulin-resistant pre-diabetes or diabetes may occur. Pulmonary restrictive disease with interstitial fibrosis may develop in addition to recurrent infections and bronchiectasis.
Variant AT has a milder course than classic AT, perhaps due to its residual ATM protein and kinase activity. 33 % of patients have retained ambulation with or without a walking aid and ability to use the arms for most activities. Extrapyramidal presentations correlated with mild disease severity.9
Specific secondary or associated conditions and complications
- Combined immunodeficiency with thymic dysplasia, decreased immunoglobulins, and reduction of T-lymphocytes occurs in 70%.
- Sinopulmonary infections occur in more than 80% of patients.4 Recurrent sinopulmonary infections and bronchiectasis alone can lead to chronic pulmonary compromise. Even in the absence of infection, patients can develop interstitial lung disease.10
- Diabetes mellitus type 2 due to insulin resistance tends to develop in the third decade.
- Somatic growth is slowed and limited with adult heights below the third percentile, and pubertal growth spurt and fertility may not occur due to hypogonadism.
- Hypopituitarism and/or hypothyroidism are not usually part of this condition.
- Lifetime risk of cancer is 38%. Cancer risks include acute lymphocytic leukemia, lymphoma, and solid tumors, with extreme sensitivity to chemotherapy and radiation therapies. In children, 85% of neoplasms are lymphomas and acute leukemias. In adults, solid tumors are more frequent.
- The average lifespan is approximately 25 years with patients succumbing to progressive pulmonary disease secondary to repeated infection or cancer. 5 Some individuals with later onset t of disease and slower progression survive into their 50s.3
ESSENTIALS OF ASSESSMENT
- Birth and early developmental history (usually normal)
- Frequent falls, clumsiness, gait abnormalities
- Frequently dropping things
- Inability to sit or stand still
- Uncontrolled eye or limb movements
- Frequent infections
- Family history will usually be negative; ask sensitively about consanguinity, other members with neurologic disorders that could be AT mimics, and cancer occurrence particularly in young adults.
- General: Small size, low weight.
- HEENT: Possible microcephaly, conjunctival telangiectasias (not before 3-5 years), small tonsils.
- Chest: abnormal breath sounds, congestion.
- Neurologic: Initially intact sensation and negative Romberg, but may later develop proprioceptive and vibratory loss. Look for truncal ataxia followed by dysmetria, dystonia especially in the hands and fingers, bradykinesia, facial and proximal hypotonia, choreoathetosis and myoclonic jerks on intention. Decreased or absent muscle stretch reflexes may be noted after age 7-8. Babinskis may eventually become upgoing, or mute.
- Ophthalmologic exam findings include oculomotor apraxia, slow hypometric saccades, head tilt, turn, or thrust, forced blinking, and absent optokinetic nystagmus. Strabismus may develop. Seborrheic blepharitis may be noted later.
- Orthopedic effects include equinovarus positioning with tight heel cords and postural kyphosis. Scoliosis is uncommon. Gait may show initial contact with whole foot, stomping, and leaning forward in running.
- Look for skin and hair progeric changes, such as gray hair and atrophic and inelastic skin, plus cutaneous telangiectasias, and sometimes hirsutism in women. Children with AT frequently have café-au-lait macules.
|Findings Seen in:||First Decade||Second Decade|
|Mobility||Ambulates with walker Ankle-foot orthoses: solid or articulated Frequent falls||Wheelchair use more often; may need power chair depending on progression.|
|Self-care||Uses utensils Progressive oral and pharyngeal dysphagia Assistance for dressing/toileting||May lose self-feeding and swallowing abilities; gastrostomy placement may be needed Drooling Dependent for most activities of daily living|
|Communication||Speaks softly in sentences Slow, with monotone, “scanning” dysarthria Hypomimia (limited facial expression) Fatigues with writing||Can communicate verbally but with severe fatigue Poor respiratory control May lose abilities to read and write|
|Social interaction||Friendly, shy Responsive, appreciative, undemanding||Good sense of humor May be limited by severe fatigue|
|Cognition||Slow information processing Learns well auditorily||Measured IQ may decline Short-term memory loss may develop|
Consider this diagnosis in cases of progressive ataxia or “ataxic cerebral palsy” that worsen or develop additional neurologic findings.
- Elevated serum alpha-fetoprotein >2 standard deviations above normal is a fairly specific screen. It is also seen in some of the other autosomal recessive ataxias such as ataxia with oculomotor apraxia.
- Molecular genetic testing for the specific trinucleotide expansion of Friedreich ataxia, serum albumin, cholesterol, very long chain fatty acids, ceruloplasmin and copper studies, lactate/pyruvate and coenzyme Q10 levels may be determined to look for other entities which may be in the differential diagnosis.
- Definitive diagnosis is usually made by ATM gene sequencing.
- Immunoblotting for ATM protein, cell culture radiosensitivity, chromosomal studies for breakage and translocations often involving chromosomes 7 and 14 may be available in some centers.
- White blood cell analysis shows lymphopenia with prominent reduction in T-cells.
- Immunoglobulin analysis can show Oligoclonal gammopathies, deficiencies of immunoglobulin E, immunoglobulin G subclass 2, and immunoglobulin A with some increases in IgM.
- Inability to produce antibodies to polysaccharide antigens locating on the capsule of pathogenic bacteria such as the pneumococcus. 3
Avoid x-rays whenever possible due to radiosensitivity.
Brain Magnetic resonance imaging
- Early: normal.
- Later: progressive cerebellar atrophy; small scattered hypointensities suggestive of capillary telangiectasia and basal gangliar lesions may appear.1,11
- Second and third decades: marked extracerebellar hyperintense lesions in the cerebral white matter, pontine, and spinal atrophy.
- Increased choline signal intensity (magnetic resonance spectroscopy) in 12 adults.4
Lung MRI: bronchiectasis, consolidation in later stage.
Early predictions of outcomes
Early diagnosis of AT is important for initiation of surveillance for cancer and prevention of ionizing radiation damage. There are over 600 variant mutations, and phenotype severity seems to vary with ATM protein levels. Protein assays may become available to help predict prognosis.1,7
Identify barriers to participation including stairs, door width, uneven terrain, loose rugs, counter height, bath and toilet equipment, and hand rails. Ask about environmental exposures that could increase the risk of various cancers, such as prolonged UV light exposure.
Social role and social support system
Parents should be asked about the emotional and psychologic stresses of parenting a child with a degenerative disease and offered any assistance and support available in the community, as well as encouragement to connect with other families affected by this condition via online support groups.
Heterozygotes with disease-causing mutations in ATM have a cancer risk 4 times that of the general population3 and are at risk for transmitting the mutation to their children.13 Patients with AT and their female family members with heterozygous mutant ATM should be advised to start the screening for breast cancer at an earlier age. This age can be determined by considering the type of the mutation in the ATM gene. 14 Do not overestimate cognitive decline based on facial expression and speech production.
REHABILITATION MANAGEMENT AND TREATMENTS
Available or current treatment guidelines
Genetic therapy for ATM is not available, no therapies significantly alter the course of the disease, and no specific treatment exists for the ataxic syndrome or the progressive neurodegeneration. However, cancer surveillance, nutritional support, and management of immunodeficiency may greatly improve health and well-being. Rehabilitation therapies and management of other movement disorders and abnormal tone may promote better functional abilities. Physiotherapy and exercise are vital to maintain muscle strength and to prevent joint contractures, whereas occupational therapists can provide appropriate aids and devices for daily activities and an adequate sitting position. 8
Therapeutic strategies for variant ataxia-telangiectasia with extrapyramidal movement disorders are similar to those used in the no variant form. 14
- Preventing deterioration, including promoting activity to preserve strength and endurance, and stretching to delay or reverse progressive deformities of the feet.
- Teaching compensatory strategies to decrease effects of ataxia, tremor, dysphagia, and dysarthria.
- Enabling academic participation and success.
- Monitoring for and managing cancer, pulmonary disease, and immune deficiencies.
- Minimizing use of x-rays and environmental exposure to ionizing radiation.
- Bathroom: shower chair, toilet rails, tub bar, modified sinks for wheelchair access, mirror at eye level, bath mitt, liquid soap, urinal built-up handles, wider door frames, tiled floors, and wheelchair use at table and computer.
- Eating: weighted, large-handled utensils, bent-angled spoons, bowl with suction cup, sticky-type place mat to stabilize plates, and plate platform to decrease hand to mouth distance.
- Mobility: walker, gait trainer, manual chair with solid or slightly contoured seat and back, lateral trunk supports, headrest and forearm supports, and power chair when unable to propel.
At different disease stages
- Permit whole-handed grasp of spoon.
- Finger foods and textures easy to self-feed.
- Electric toothbrush.
- Modify clothing to simplify dressing and toileting.
- Encourage truncal stabilization: arms close to body and elbows on table.
- Discourage unhelpful compensatory strategies.
- Special education (Individual education program, IEP) and/or Section 504 evaluation should address cognitive, fine, gross motor, activities of daily living, speech and language, and modifications for academic testing to extend time limits to accommodate patient’s need.
- Serial neuropsychological evaluations.
- Teach child to recognize and communicate the need for increased time and fatigue.
- Less course work, shortened days, personal aide for safety, scribing notes, increased time for assignments, and computer use.
- Cultivate critical listening, auditory learning strategies, and oral testing.
- Communicate and give directions to follow with short key word phrases.
- Oral motor strengthening for eating, speech, and control of secretions.
- Breathing exercises to improve voice production.
- Continued exposure to vocabulary and semantic or phonemic cues to assist word finding.
- People with AT are able to communicate effectively throughout life and rarely need augmentative communication devices.
- Wrap-around desk that supports forearms.
- Slant board at 45° degrees for upper-extremity stability.
- Computer access with appropriate keyboard and mouse.
- Auditory feedback software such as IntelliTalk and Write:Outloud talking word processing
- Optical character recognition or screen reading software
- Modified barium swallow.
- Advance enteral feeds slowly after gastrostomy when needed for nutritional support, and permit any oral intake as safely possible.
- Interventions should focus on increasing oral intake along with diet quality while also minimizing risk of aspiration, which include resting in the afternoons to ensure the patient is not too fatigued to eat dinner, cutting food into bite sized portions to avoid chewing fatigue, serving soft foods, thickening thin liquids, and using a straw to avoid choking.15
Preterminal or end of life care
- Noninvasive ventilation.
- Home-bound instruction.
Treatment outcome assessment tools include:
- Scale for Assessment and Rating of Ataxia (SARA).
- International Cooperative Ataxia Rating Scale.
- Semi-quantitative measures, such as timing of:
- Single-leg stance.
- Hand and foot tapping.
- Maze or pegboard.
- Paragraph reading.
Coordination of care
When possible, children are best served by interdisciplinary cooperation. The ideal team would include the following:
- Geneticist and genetic counselors aid in making the diagnosis and family planning issues.
- Physiatrists and neurologists to recommend and prescribe therapies, orthotics, assistive devices, durable medical equipment, and environmental modifications, therapeutic trials of medications to manage abnormal tone and movement.
- Developmental pediatrician and/or neuropsychologist to assess specific academic and/or behavioral school accommodations
- Physical therapist and occupational therapist: safety, energy efficiency, and appropriate physical independence.
- Speech language therapist: feeding and communication.
- Immunologist: gamma globulin infusions, pneumococcal, flu, and other vaccines.
- Oncologist: CBC q 3 months.
- Pulmonologist: pulmonary function tests, antibiotics prophylaxis.
- Effective social work and/or case management to help connect with local resources including respite care and advocacy, and assess eligibility for state funding and insurance coverage options.
- Referral to information resources, family support groups.
- Ataxia-Telangiectasia Children’s Project (http://www.communityatcp.org/, http://www.atcp.org)
- National Ataxia Foundation (http://www.ataxia.org/)
- Ataxia-Telangiectasia Clinical Center at Johns Hopkins (http://www.hopkinschildrens.org/Ataxia-Telangiectasia.aspx)
Patient & family education
- Promote respect for the child’s need for extra processing time.
- Understand organic nature of fatigue.
- Encourage child to communicate need for extra time.
- Develop signs and key words to communicate.
- Avoidance of x-rays and unprotected sun or other environmental exposures.
- Benefits of maintaining activity as tolerated for preserving strength, and other compensation for ataxia.
- Whole family vaccination.
Therapeutic trials (ATTeST study) are ongoing to test the efficacy of treatment with dexamethasone to improve neurological symptoms. The innovative ways of delivery such patients’ autologous red blood cells loaded with dexamethasone allow the slow release of dexamethasone, and avoid the side effects of long-term administration of steroids. 3, 16
Translation into practice: practice “pearls”/performance improvement in practice (PIPs)/changes in clinical practice behaviors and skills
AT should be considered in children who present with progressive ataxia, even if telangiectasia is not obvious. Alpha fetoprotein should be ordered as part of an ataxia workup. Not only ataxia but the other movement disorders which emerge need to be addressed. Referrals for immunologic and oncologic care and surveillance are critical.
CUTTING EDGE/EMERGING AND UNIQUE CONCEPTS AND PRACTICE
Cutting edge concepts and practice
- Amantadine: well-tolerated and effective treatment for motor symptoms (ataxia, involuntary movements, dysarthria).17
- Betamethasone: 0.03 mg/kg/day for 10 days significantly improved SARA scores and demonstrated increased cortical activation on functional magnetic resonance imaging.18
- Dopamine agonists or anticholinergics: extrapyramidal movements.1,11,18
- Baclofen: eye movements and tremor.1,11
- Gabapentin, clonazepam, and propranolol: tremors.1,11
- Fluoxetine or buspirone: speech and balance.18
- Trihexyphenidyl may be helpful for general dystonia, botulinum toxin A is the first –choice treatment for focal dystonia. 8
Stem-cell transplantation can correct immunological abnormalities. 8
Therapy: there is class III evidence that coordinative training improves motor performance and reduces ataxia symptoms.19
GAPS IN THE EVIDENCE-BASED KNOWLEDGE
Gaps in the evidence-based knowledge
No specific treatment exists for the ataxic syndrome or the progressive cerebellar neurodegeneration. 6 Drug therapies are actually based on small therapeutic trials. In the absence of curative or strong evidence-based treatment, recommendations at present are based on expert consensus and use for similar signs and symptoms in other neurological disorders.1 Metabolic derangements in brain tissue are being explored as possible therapeutic targets. Gene therapy for AT remains theoretical and stem cell therapies are controversial at this time.20,21
- Hoche F, Seidel K, Theis M, et al. Neurodegeneration in ataxia telangiectasia: what is new? What is evident? Neuropediatrics. 2012;43:119-129.
- Teive H.A.G., Moro A, Moscovich M, Munhoz R, Ashizawa T. Ataxia- telangiectasia- A historical review and a proposal for a new name: ATM syndrome. J Neurol Sci. 2015 Aug 15; 355(1-2): 3–6.
- Riboldi G M, Samanta D, Frucht S. In NCBI bookshelf: Ataxia telengiectasia ( Loiis- Bar Syndrome). Last update Feburary 21, 2020. https://www.ncbi.nlm.nih.gov/books/NBK519542/
- .Verhagen, M. M. M et al., Presence of ATM protein and residual kinase activity correlates with the phenotype in ataxia-telangiectasia: A genotype–phenotype study. Hum. Mutat. 2012;33: 561–571.
- Crawford TO, Skolasky RL, Fernandez R, et al. Survival probability in ataxia telangiectasia. Arch Dis Child 2006; 91:610.
- Opal P, Patterson M, Dashe J. Ataxia- telangiectasia Uptodate Feb 2020 https://www.uptodate.com/contents/ataxia-telangiectasia?search=ataxia%20telangiectasia&source=search_result&selectedTitle=1~150&usage_type=default&display_rank=1
- Vinck A, Verhagen MM, Gerven Mv, et al. Cognitive and speech-language performance in children with ataxia telangiectasia. Dev Neurorehabil 2011; 14:315.
- Van OS NJH, Haaxma CA, Van der Flier M, et al. Ataxia-telangiectasia: recommendations for multidisciplinary treatment. Dev Med Child Neurol. 2017 Jul;59(7):680-689.
- McConville CM, Stankovic T, Byrd PJ, et al. Mutations associated with variant phenotypes in ataxia-telangiectasia. Am J Hum Genet 1996; 59:320.
- McGrath-Morrow SA, Gower WA, Rothblum-Oviatt C, et al. Evaluation and management of pulmonary disease in ataxia-telangiectasia. Pediatr Pulmonol 2010; 45:847.
- Wallis LI, Griffiths PD, Ritchie SJ, Romanoski CA, Darwent G, Wilkinson ID. Proton spectroscopy and imaging at 3T in ataxia-telangiectasia. AJNR Am J Neuroradiol. 2007;28:79-83.
- Fanos JH, Mackintosh MA. Never again joy without sorrow: the effect on parents of a child with ataxia- telangiectasia. Am J Med Genet. 1999;87:413-419.
- A-T Children’s Project. A-T caregiver handbook. Available at: http://www.communityatcp.org/page.aspx?pid=3509. Accessed August 14, 2012.
- van Os NJ, Roeleveld N, Weemaes CM, et al. Health risks for ataxia-telangiectasia mutated heterozygotes: a systematic review, meta-analysis and evidence-based guideline. Clin Genet 2016; 90:105.
- Ross LJ, Capra S, Baguley B, et al. Nutrition status of patients with ataxia-telangiectasia: a case study for early and ongoing nutritional support and intervention. J Paediatr Child Health 2015; 51: 802-807.
- Chessa L, Micheli R, Molinaro A. Focusing New Ataxia Telangiectasia Therapeutic Approaches. J Rare Dis Diagn Ther. 2016, 2:2.
- Nissenkorn A, Hassin-Baer S, Lerman SF, Banet Levi Y, Tzadok M, Ben-Zeev B. Movement disorder in ataxia-telangiectasia: treatment with amantadine sulfate. J Child Neurol. 2013;28:155-160.
- Broccoletti T, Del Giudice E, Cirillo E, et al. Efficacy of very-low-dose betamethasone on neurological symptoms in ataxia-telangiectasia. Eur J Neurol. 2011;18:564-570.
- Quaranrelli M, Giardino G, Prinster A, et al. Steroid treatment in ataxia-telangiectasia induces alterations of functional magnetic resonance during prono-supination task. Eur J Paediatr Neurol. 2013;17:135-140.
- Amariglio N, Hirshberg A, Scheithauer BW, et al. Donor-derived brain tumor following neural stem cell transplantation in an ataxia telangiectasia patient. PLoS Med. 2009;6:e1000029.
- Ghosh S, Schuster FR, Binder V, et al. Fatal outcome despite full lympho-hematopoietic reconstitution after allogeneic stem cell transplantation in atypical ataxia telangiectasia. J Clin Immunol. 2012;32:438-440.
Ilg W, Synofzik M, Bratz D, Burkard S, Giese MA, Schols L. Intensive coordinative training improves motor performance in degenerative cerebellar disease. Neurology. 2009;73:1823-1830
Lavin MF, Gueven N, Bottle S, Gatti RA. Current and potential therapeutic strategies for the treatment of ataxia-telangiectasia. Br Med Bull. 2007;81-82:129-147.
Mancebo E, Bernardo I, Castro MJ, et al. Rapid molecular prenatal diagnosis of ataxia-telangiectasia by direct mutational analysis. Prenat Diagn. 2007;27:861-864.
McKinnon P. ATM and the molecular pathogenesis of ataxia telangiectasia. Annu Rev Pathol. 2012;7:303-321.
Nissenkorn A, Levi YB, Vilozni D, et al. Neurologic presentation in children with ataxia-telangiectasia: is small head circumferance a hallmark of the disease? J Pediatr. 2011;159:466-471.
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Original Version of the Topic:
Barbara Wechsler, MD, Monika Y. Patel, MD, Adiaha Spinks-Franklin, MD, MPH. Ataxia telangiectasia. Publication Date: 2013/04/12.
Previous Revision(s) of the Topic
Vikki A. Stefans, MD. Ataxia telangiectasia. Publication Date: 08/22/2016.
Yuxi Chen, MD
Ipsen: Research Grant paid to institution, PI for Pediatric lower limb spasticity study
Clayton Mucha, DO
Nothing to Disclose
Devin Oakes, DO
Nothing to Disclose