Friedreich ataxia (FRDA)FFriedreich ataxia (FRDA)Friedreich ataxia (FRDA)EnglishGenetics;NeurologyChild (0-12 years);Teen (13-18 years)BodyNervous system;Muscular systemConditions and diseasesAdult (19+) CaregiversNA2020-01-06T05:00:00ZGrace Yoon, MD, FRCPC9.6000000000000051.60000000000001865.00000000000Health (A-Z) - ConditionsHealth A-Z<p>Learn about the genetic neuromuscular disorder called Friedreich ataxia (FRDA).</p><h2>What is ataxia?</h2><p>Ataxia is a movement disorder. Movement disorders are conditions that cause involuntary body movements. Uncontrolled movement starts in the brain, in the area you use to move, speak and pay attention. When children have ataxia, they have trouble controlling their muscles and can be clumsy and awkward.</p><h2>What is Friedreich ataxia?</h2><p>Friedreich ataxia (FRDA) is an inherited condition that causes loss of muscle coordination (ataxia), slurred speech (dysarthria), weakness and sensory loss. Symptoms usually begin between ages five and 15, with most diagnoses made before age 25. Occasionally, symptoms begin in adults over 30 or in children younger than five years of age. Although it is a rare disorder, FRDA is the most common form of inherited childhood onset ataxia, occurring in about 1 in 40,000 people. In some regions or ethnic groups, this number might be a little higher or lower. The time that it takes for FRDA to progress happens at different speeds in different children and can eventually impair day-to-day life.</p><h2>Key points</h2><ul><li>FRDA is an inherited condition that causes slow, progressive loss of muscle coordination (ataxia), slurred speech (dysarthria), weakness and sensory loss. The rate of progression of FRDA varies from person to person.</li><li>Symptoms usually begin between ages five and 15, with most diagnoses made before age 25.</li><li>Many of the symptoms and accompanying complications can be treated to help individuals maintain optimal functioning for as long as possible.</li><li>FRDA is the most common form of inherited childhood-onset ataxia, occurring in about 1 in 40,000 people. In some regions or ethnic groups, this number might be a little higher or lower.</li><li>FRDA is caused by an alteration (mutation) in a gene called <em>FXN</em>. The <em>FXN</em> gene carries the instructions for making a protein called frataxin, which is necessary for the body to function properly.</li></ul><h2>Signs and symptoms of Friedreich ataxia</h2><p>Children with FRDA may show some or all of the following signs and symptoms:</p><ul><li>Curvature of the spine (<a href="/Article?contentid=2006&language=English">scoliosis</a>) and foot deformities (high arches in the feet called “pes cavus”)</li><li>Difficulty knowing where their hands and feet are in space (impaired position sense), leading to difficulties with balance and coordination</li><li>Weakness in the legs and hands</li><li>Mild to severe <a href="/Article?contentid=1576&language=English">heart problems</a>, such as thickening of the heart muscle (<a href="/Article?contentid=1629&language=English">cardiomyopathy</a>)</li><li>Hearing loss</li><li>Changes in vision</li><li>Problems with bladder control</li><li>Fatigue</li><li>Difficulty speaking</li><li><a href="/Article?contentid=1717&language=English">Diabetes</a></li></ul><h2>Friedreich ataxia is a genetic disease</h2> <figure><span class="asset-image-title">What are genes?</span><img src="https://assets.aboutkidshealth.ca/akhassets/What_is_a_gene_MED_ILL_EN.jpg" alt="A cell, chromosome, DNA strand, gene, and DNA building blocks (called nucleotides)" /><figcaption class="asset-image-caption">Genes are made of long strings of nucleotides on a section of DNA. Groups of genes are packed tightly in a chromosome.</figcaption> </figure> <p>FRDA is an inherited condition, meaning it is passed from parents to their children through genes. Genes are the instructions that our cells use to make proteins. They tell our cells how to work and what to do. For example, one gene may determine the colour of your hair or your blood type. Each person carries two copies of each gene. A child gets (inherits) one copy from their mother and the other from their father.</p><p>FRDA is caused by the mutation of a gene called <em>FXN</em>, which makes a protein called frataxin. Normally, people have two working copies of the <em>FXN</em> gene. Children with FRDA have two non-working copies.</p><p>FRDA occurs in a child only if both parents are carriers; that is, if both parents carry one normal (working) version of the <em>FXN</em> gene and one mutated (non-working) version of the <em>FXN</em> gene. FRDA is a recessive condition, which means that both parents have passed down their mutated <em>FXN</em> gene to their child.</p><p>Most parents do not know that they carry the mutated <em>FXN</em> gene because they have only one copy of it. This makes them carriers of FRDA. They are unaffected and do not have any symptoms of the condtition. In fact, most carriers are unaware of their carrier status until they have a child with FRDA. If both carrier parents pass the mutated <em>FXN</em> gene to their child, that child will have FRDA. In each pregnancy, carrier couples have a one-in-four chance of having a child with FRDA, a one-in-two chance of having a child who is a carrier of FRDA, and a one-in-four chance of having a child who is not a carrier of FRDA nor has the condition.</p> <figure class="asset-c-80"> <span class="asset-image-title">Inheritance pattern of Friedreich ataxia</span><img src="https://assets.aboutkidshealth.ca/AKHAssets/FriedreichAtaxia.jpg" alt="Inheritance pattern of two parents who are carriers of Friedreich ataxia, producing three possible combinations" /><figcaption class="asset-image-caption">Friedreich ataxia is caused by the mutation of a gene called <em>FXN</em>. The ‘R’ above represents the working <em>FXN</em> gene and the ‘r’ represents the recessive non-working <em>FXN</em> gene.</figcaption> </figure> <p>For more information about genes, please see the AboutKidsHealth section on <a href="https://www.aboutkidshealth.ca/body/interactive?module=genetics">How the Body Works: Genetics</a>.</p><h2>Diagnosis</h2><p>There are many types of mutations that can lead to genetic disorders. In the case of FRDA, the mutation comes from the addition of genetic material. The mutated <em>FXN</em> gene is much longer than the normal gene. A normal <em>FXN</em> gene contains a three base sequence (GAA) that is repeated five to 33 times in the DNA. These are the instructions for the body to produce the protein frataxin. The instructions for the mutated version of the <em>FXN</em> gene are much longer, and the sequence is repeated between 66 and 1700 times. This causes the gene to turn off, which stops the production of frataxin. Without frataxin, the nerves in the brain and spinal cord become damaged.</p><p>To confirm a diagnosis, children suspected of having FRDA can have a genetic blood test to determine whether or not they have the mutated gene. The test looks specifically at the <em>FXN</em> gene to determine if there is a mutation. Children with one normal <em>FXN</em> gene and 34 to 65 repeated sequences on the other gene are said to have a “premutation”. They do not show any symptoms of FRDA; however, there is an increased chance for the repeated sequence size to increase in their reproductive cells. This means that they are potential carriers of the disorder and could have a future child with FRDA. Children with 44 to 66 repeated sequences on one <em>FXN</em> gene may, develop FRDA later in life if the second copy of the gene is mutated.</p><p>In some cases, a child may have a different type of genetic mutation that also causes FRDA called a point mutation or “spelling mistake” in the <em>FXN</em> gene. Further testing may be needed if your child has this type of mutation.</p><p>Other tests that may help in the diagnosis of FRDA include the following:</p><ul><li>Electromyogram (EMG), a test for measuring the electrical activity of muscle cells</li><li> <a href="/Article?contentid=1283&language=English">Nerve conduction studies</a>, tests measuring the speed of impulses transmitted by nerves</li><li> <a href="/Article?contentid=1276&language=English">Electrocardiogram</a> (also called EKG or ECG), a test that measures the electrical activity of the heart</li><li> <a href="/Article?contentid=1274&language=English">Echocardiogram</a>, a test using sound waves to take pictures of the heart</li><li>Blood tests to check for elevated glucose levels and vitamin E levels</li><li> <a href="/Article?contentid=1270&language=English">Magnetic resonance imaging (MRI)</a> or <a href="/Article?contentid=1272&language=English">computed tomography (CT) scans</a>, tests that take pictures of the brain and spinal cord</li></ul><h3>Related conditions</h3><p>Some other conditions that can look like FRDA include: ataxia with vitamin E deficiency; abetalipoproteinemia, Refsum disease; infantile onset spinocerebellar ataxia; ataxia-telangiectasia; and many others. A geneticist can help to make a definitive diagnosis.</p><h2>Treatment</h2><p>There is currently no cure for FRDA, but there are symptom treatments that can help maintain optimal functioning for as long as possible. FRDA is managed by ensuring proper care is given to the systems of the body that can be affected by the condition. This includes regular follow-up with a neurologist, a cardiologist (to monitor for heart problems) and an endocrinologist (hormone specialist to monitor for diabetes). Children with scoliosis will also need to be monitored by an orthopedic surgeon. Some diabetes and heart complications can be managed with medications, and research suggests that taking antioxidants may also help with heart-related problems in FRDA.</p><p>Physiotherapy is recommended to help monitor and maintain range of motion, and to help design an appropriate exercise program. An occupational therapist can assist with alternative communication and walking aids, and they can also assess safety risks in the home.</p><p>These symptom treatments can help improve your child’s quality of life by reducing the severity of the complications associated with FRDA. To develop the best treatment plan for a child with FRDA, parents, doctors, teachers, therapists and other family members should work closely together in the best interest of the child.</p><h2>Complications</h2><p>FRDA is a progressive condition that breaks down the muscles and nerves of the body over time. It does not affect intelligence, and the rate of progression happens at different speeds in different children. Children with FRDA experience a loss of muscle coordination (ataxia) and feel off-balance when walking. They may have difficulty knowing where their hands and feet are in space, and may develop weakness in their legs and hands. Curvature of the spine (scoliosis), slurred speech, stiffness of the lower limbs, loss of joint sensation, loss of sensation in the legs and feet, and difficulty controlling bowel and bladder function may develop over time.</p><p>More than half of individuals with FRDA also have a heart condition called <a href="/Article?contentid=1629&language=English">hypertrophic cardiomyopathy</a>. This can be associated with an abnormal heart rhythm, so routine follow-up with a cardiologist is important. Some individuals with FRDA can develop diabetes, so regular screening through blood work is also important. Other features include vision changes and/or hearing loss.</p><h2>At SickKids</h2><p>SickKids has a special multi-disciplinary clinic for children with FRDA and their families. The clinic takes place in the cardiology department, and it is staffed by a cardiologist, nurse practitioner, geneticist and genetic counsellor who have experience taking care of children with FRDA. Cardiac evaluations including EKG; echocardiograms and Holtor monitoring; a detailed neurological examination; assessment of quality of life and well-being; and bloodwork to screen for complications of FRDA, such as diabetes, are performed during each annual visit.</p><h2>Resources</h2><p>For more information on FRDA, visit the following websites:</p><p> <strong> <u>Canada</u></strong></p><p>Muscular Dystrophy Canada<br> <a href="http://www.muscle.ca/">www.muscle.ca</a></p><p>Ataxia Canada<br> <a href="https://lacaf.org/en/about-us-2/">www.lacaf.org</a></p><p> <strong> <u>International</u></strong></p><p>Friedreich's Ataxia Research Alliance (FARA)<br> <a href="https://www.curefa.org/">www.curefa.org</a></p><p>euro-ataxia (European Federation of Hereditary Ataxias)<br> <a href="http://www.euro-ataxia.org/">www.euro-ataxia.org</a></p><p>Muscular Dystrophy Association (MDA)<br> <a href="http://www.mdausa.org/">www.mdausa.org</a></p><p>National Ataxia Foundation<br> <a href="http://www.ataxia.org/">www.ataxia.org</a></p><h2>References</h2><p>National Institute of Neurological Disorders and Stroke (2018, June). <em>Friedreich's Ataxia Fact Sheet</em>. Retrieved from <a href="https://www.ninds.nih.gov/Disorders/Patient-Caregiver-Education/Fact-Sheets/Friedreichs-Ataxia-Fact-Sheet#3070_3">https://www.ninds.nih.gov/Disorders/Patient-Caregiver-Education/Fact-Sheets/Friedreichs-Ataxia-Fact-Sheet#3070_3</a></p><p>National Organization for Rare Disorders (2018). <em>Rare Disease Database: Friedreich’s Ataxia</em>. Retrieved from <a href="https://rarediseases.org/rare-diseases/friedreichs-ataxia/">https://rarediseases.org/rare-diseases/friedreichs-ataxia/</a></p><p>Muscular Dystrophy Canada (2019). <em>Types of Neuromuscular Disorders: Friedreich’s Ataxia</em>. Retreived from <a href="http://muscle.ca/discover-md/types-of-neuromuscular-disorders/">http://www.muscle.ca/about-muscular-dystrophy/types-of-neuromuscular-disorders/</a></p><p>Ataxia Canada (2014, June). <em>Cardiac problems in Friedreich’s Ataxia</em>. Retreived from <a href="https://lacaf.org/en/cardiac-problems-in-friedreich-ataxia/">https://lacaf.org/en/cardiac-problems-in-friedreich-ataxia/</a></p><p>Corben LA, Lynch D, Pandolfo M, et al (2014). Consensus clinical management guidelines for Friedreich ataxia. <em>Orphanet J Rare Dis, 9</em>: 184.</p>
Ataxie de Friedreich (AF)AAtaxie de Friedreich (AF)Friedreich ataxia (FRDA)FrenchGenetics;NeurologyChild (0-12 years);Teen (13-18 years)BodyNervous system;Muscular systemConditions and diseasesAdult (19+) CaregiversNA2020-01-06T05:00:00ZGrace Yoon, MD, FRCPC2181.00000000000Health (A-Z) - ConditionsHealth A-Z<p>Découvrez le trouble neuromusculaire génétique appelé ataxie de Friedreich (AF).</p><h2>Qu’est-ce que l’ataxie?</h2><p>L’ataxie est un trouble de la coordination des mouvements. Les troubles du mouvement sont des états de santé caractérisés par des mouvements involontaires du corps. Les mouvements incontrôlés commencent dans le cerveau, dans la zone qui permet de bouger, de parler et d’être attentif. Les enfants qui présentent les symptômes d’ataxie ont du mal à contrôler leurs muscles et peuvent sembler maladroits.</p><h2>Qu’est-ce que l’ataxie de Friedreich?</h2><p>L’ataxie de Friedreich est une maladie héréditaire qui se manifeste par une perte de coordination musculaire (ataxie), des troubles de l’élocution (dysarthrie), une faiblesse et une perte sensorielle. En général, les premiers symptômes apparaissent entre cinq et quinze ans, et la plupart des diagnostics sont effectués avant l’âge de 25 ans. Parfois, les symptômes commencent chez les adultes de plus de 30 ans ou chez les enfants de moins de cinq ans. Certes, il s’agit d’un trouble rare, mais l’AF est la forme la plus courante d’ataxie héréditaire de l’enfant. Elle survient chez environ 1 personne sur 40 000. Dans certaines régions ou certains groupes ethniques, ce nombre peut être un peu plus élevé ou plus bas. La vitesse de progression de l’AF varie d’un enfant à l’autre et peut au bout du compte nuire aux activités quotidiennes.</p><h2>Points clés</h2><ul><li>L'AF est une maladie héréditaire qui se manifeste par une perte lente et progressive de coordination musculaire (ataxie), des troubles de l'élocution (dysarthrie), une faiblesse et une perte sensorielle. La vitesse de progression de l’AF varie d'une personne à l'autre.</li><li>En général, les premiers symptômes apparaissent entre cinq et quinze ans, et la plupart des diagnostics sont effectués avant l'âge de 25 ans.</li><li>La plupart des symptômes et complications connexes peuvent être traités afin de permettre aux patients de fonctionner pleinement le plus longtemps possible.</li><li>La maladie de Friedreich est la forme la plus courante d’ataxie héréditaire de l’enfant. Elle survient chez environ 1 personne sur 40 000. Dans certaines régions ou certains groupes ethniques, ce nombre peut être un peu plus élevé ou plus bas.</li><li>Cette maladie est causée par une altération (mutation) d’un gène appelé <em>FXN</em>. Le gène <em>FXN</em> transporte les instructions pour la production de la frataxine, une protéine nécessaire au bon fonctionnement du corps.</li></ul><h2>Signes et symptômes de l’AF</h2><p>Les enfants atteints de l’AF peuvent présenter tout ou partie des signes et symptômes suivants :</p><ul><li>Déviation de la colonne vertébrale (<a href="/Article?contentid=2006&language=English">scoliose</a>) et déformations du pied (voûte plantaire prononcée ou « pieds creux »)</li><li>Difficulté à se rendre compte de la position des mains et des pieds (altération du sens de la position), ce qui entraîne des problèmes d’équilibre et de coordination</li><li>Affaiblissement des jambes et des mains</li><li> <a href="/Article?contentid=1576&language=English">Problèmes cardiaques</a> modérés à sévères, comme l’épaississement du muscle cardiaque (<a href="/Article?contentid=1629&language=English">cardiomyopathie</a>)</li><li>Perte d’audition</li><li>Troubles de la vision</li><li>Difficultés de contrôle de la vessie</li><li>Fatigue</li><li>Difficultés d’élocution</li><li> <a href="/Article?contentid=1717&language=English">Le diabète</a></li></ul><h2>L’ataxie de Friedreich est une maladie génétique</h2> <figure> <span class="asset-image-title">Qu’est-ce qu’un gène?</span><img src="https://assets.aboutkidshealth.ca/AKHAssets/Gene_mutations_MED_ILL_FR.jpg" alt="A cell, chromosome, DNA strand, gene, and DNA building blocks (called nucleotides)" /><figcaption class="asset-image-caption">Les gènes sont constitués de longs brins de nucléotides sur une section d’ADN. Des groupes de gènes sont densément localisés dans un chromosome.</figcaption></figure> <p>L’AF est une maladie héréditaire, c’est-à-dire qu’elle est transmise des parents à leurs enfants par de gènes. Les gènes représentent les instructions que les cellules utilisent pour fabriquer des protéines. Ils expliquent à nos cellules comment travailler et quoi faire. Par exemple, un gène peut indiquer la couleur de vos cheveux ou votre groupe sanguin. Chaque personne porte deux copies de chaque gène. Un enfant obtient (hérite) une copie de sa mère et l’autre de son père.</p><p>L’AF est causée par la mutation du gène <em>FXN</em>, qui fabrique une protéine appelée frataxine. Normalement, les gens ont deux copies fonctionnelles du gène <em>FXN</em>. Les enfants présentant l’AF disposent de deux copies non fonctionnelles.</p><p>L’AF survient chez l’enfant uniquement si les deux parents sont porteurs, c’est-à-dire si les deux parents sont porteurs d’une version normale (fonctionnelle) du gène <em>FXN</em> et d’une version mutée (non fonctionnelle) de celui-ci. L’AF est un état récessif, ce qui signifie que les deux parents ont transmis leur gène <em>FXN</em> muté à l’enfant.</p><p>La plupart des parents ne savent pas qu’ils sont porteurs de ce gène, car ils n’en ont qu’une seule copie. Cela veut dire qu’ils sont porteurs de l’AF. Ils ne sont pas affectés et ne présentent aucun symptôme de la maladie. En effet, la plupart des porteurs ne connaissent pas leur statut de jusqu’à ce qu’un de leurs enfants reçoive le diagnostic de l’AF. Si les deux parents porteurs transmettent le gène <em>FXN</em> muté à leur enfant, cet enfant présentera la maladie de Friedreich. Pour chaque grossesse, les couples porteurs ont une chance sur quatre d’avoir un enfant atteint de l’AF, une chance sur deux d’avoir un enfant porteur de l’AF et une chance sur quatre d’avoir un enfant non porteur de l’AF ni de la maladie.</p> <figure class="asset-c-80"> <span class="asset-image-title">Profil de transmission de l’ataxie de Friedreich</span><img src="https://assets.aboutkidshealth.ca/AKHAssets/FriedreichAtaxia_FR.jpg" alt="Inheritance pattern of two parents who are carriers of Friedreich ataxia, producing three possible combinations" /><figcaption class="asset-image-caption">L’ataxie de Friedreich est causée par la mutation d’un gène appelé <em>FXN</em>. Le « R » ci-dessus représente le gène <em>FXN</em> fonctionnel, alors que « r » représente le gène <em>FXN</em> récessif non fonctionnel.</figcaption></figure> <p>Pour obtenir plus d’informations sur les gènes, veuillez consulter la section <a href="https://www.aboutkidshealth.ca/body/interactive?module=genetics">Fonctionnement du corps du site Web AboutKidsHealth : Génétiques</a>.</p><h2>Diagnostic</h2><p>Il existe plusieurs types de mutations pouvant causer des troubles génétiques. Dans le cas de l’AF, la mutation provient de l’ajout de matériel génétique. Le gène <em>FXN</em> muté est visiblement plus long que le gène normal. Un gène <em>FXN</em> normal contient une séquence de trois bases (GAA) qui est répétée 5 à 33 fois dans l’ADN. Il s’agit des instructions qui permettent au corps de produire la frataxine. Les instructions relatives à la version mutée du gène <em>FXN</em> sont beaucoup plus longues et la séquence est répétée entre 66 et 1700 fois. Cela entraîne la désactivation du gène, puis arrête la production de la frataxine. En l’absence de frataxine, les nerfs du cerveau et de la moelle épinière s’endommagent.</p><p>Pour confirmer un diagnostic, les enfants suspectés d’être atteint de l’AF peuvent subir un test sanguin génétique afin de déterminer s’ils sont porteurs ou non du gène muté. En particulier, le test a pour objectif d’analyser le gène <em>FXN</em> pour déterminer s’il existe une mutation. Les enfants ayant un gène <em>FXN</em> normal et 34 à 65 séquences répétées sur l’autre gène auraient une « prémutation ». Ils ne présentent aucun symptôme de l’AF, mais il existe une possibilité accrue que le nombre de séquences répétées augmente dans leurs cellules reproductrices. Cela signifie qu’ils sont des porteurs potentiels de la maladie et pourraient avoir un futur enfant atteint de l’AF. Les enfants ayant 44 à 66 séquences répétées sur un gène <em>FXN</em> peuvent développer l’AF plus tard dans leur vie si la deuxième copie du gène est mutée.</p><p>Dans certains cas, un enfant peut avoir un type de mutation génétique différent pouvant également causer l’AF appelée mutation ponctuelle ou « faute d’orthographe » dans le gène <em>FXN</em>. Des tests supplémentaires peuvent être nécessaires si votre enfant présente ce type de mutation.</p><p>D’autres tests pouvant être utiles dans le diagnostic de l’AF sont les suivants :</p><ul><li>Électromyogramme (EMG) : test permettant de mesurer l’activité électrique des cellules musculaires</li><li><a href="/Article?contentid=1283&language=English">Études de la conduction nerveuse</a> : tests permettant de mesurer la vitesse des impulsions transmises par les nerfs</li><li><a href="/Article?contentid=1276&language=English">Électrocardiogramme</a> (également appelé ECG) : test permettant de mesurer l’activité électrique du cœur</li><li><a href="/Article?contentid=1274&language=English">Échocardiogramme</a> : test qui utilise des ondes sonores pour prendre des photos du cœur</li><li>Des analyses sanguines pour vérifier les taux de glucose élevés et de vitamine E</li><li><a href="/Article?contentid=1270&language=English">Imagerie par résonance magnétique (IRM)</a> ou <a href="/Article?contentid=1272&language=English">tomodensitométrie (TDM)</a> : tests qui permettent de prendre des photos du cerveau et de la moelle épinière</li></ul><h3>Affections connexes</h3><p>Les maladies suivantes peuvent s’apparenter à l’AF : l’ataxie avec carence en vitamine E; l’abétalipoprotéinémie, maladie de Refsum; l’ataxie spinocérébelleuse infantile; l’ataxie télangiectasie et bien d’autres. Un généticien peut aider à poser un diagnostic définitif.</p><h2>Traitement</h2><p>Il n’existe actuellement aucun remède contre l’AF, mais des traitements des symptômes sont disponibles et peuvent aider à maintenir un fonctionnement optimal le plus longtemps possible. L’AF est gérée en veillant à ce que les systèmes du corps pouvant être affectés par la maladie reçoivent les soins appropriés. Il s’agit d’assurer un suivi régulier avec un neurologue, un cardiologue (pour surveiller les problèmes cardiaques) et un endocrinologue (spécialiste des hormones pour surveiller le diabète). Les enfants atteints de scoliose devront également être suivis par un chirurgien orthopédiste. Certaines complications du diabète et du cœur peuvent être gérées en prenant des médicaments, et des recherches montrent que le fait de prendre des antioxydants peut également aider à résoudre les problèmes cardiaques liés à l’AF.</p><p>La physiothérapie est recommandée afin d’aider à surveiller et à maintenir l’amplitude des mouvements et faciliter la mise en œuvre d’un programme d’exercice approprié. Un ergothérapeute peut proposer d’autres moyens de communication et aides à la marche. Il peut également évaluer les risques pour la sécurité à la maison.</p><p>Ces traitements des symptômes peuvent permettre d’améliorer la qualité de vie de votre enfant en réduisant la gravité des complications associées à l’AF. Pour mettre au point le meilleur plan de traitement pour un enfant atteint de l’AF, les parents, les médecins, les enseignants, les thérapeutes et les membres de la famille doivent travailler en étroite collaboration dans l’intérêt supérieur de l’enfant.</p><h2>Complications</h2><p>L’AF est une maladie qui se manifeste progressivement en détériorant les muscles et les nerfs du corps au fil du temps. Cette affection n’a aucune incidence sur l’intelligence et la progression se déroule à des vitesses qui varient d’un enfant à l’autre. Les enfants présentant l’AF sont affectés par une perte de la coordination musculaire (ataxie) et se sentent déséquilibrés lorsqu’ils marchent. Ils peuvent non seulement avoir de la difficulté à savoir où se trouvent leurs mains et leurs pieds dans l’espace, mais également éprouver une faiblesse dans les jambes et les mains. Les symptômes suivants peuvent apparaître au fil du temps : déviation de la colonne vertébrale (scoliose), atteinte de la parole, raideur des membres inférieurs, perte de sensation articulaire, perte de sensation dans les jambes et les pieds et difficulté à contrôler la fonction intestinale et urinaire.</p><p>Plus de la moitié des personnes atteintes de l’AF ont également une maladie cardiaque appelée <a href="/Article?contentid=1629&language=English">cardiomyopathie hypertrophique</a>. Cet état peut être associé à un rythme cardiaque anormal. Il est donc important d’effectuer un suivi de routine avec un cardiologue. Certaines personnes présentant l’AF peuvent développer un diabète. Il est également important d’effectuer un dépistage régulier par des analyses sanguines. Les autres caractéristiques comprennent des troubles de la vision ou une perte auditive.</p><h2>SickKids</h2><p>L’hôpital SickKids possède une clinique multidisciplinaire spéciale pour les enfants atteints de l’AF et leurs familles. La clinique se déroule dans le service de cardiologie et son personnel inclue un cardiologue, une infirmière praticienne, un généticien et un conseiller en génétique qui ont de l’expérience dans la prise en charge des enfants atteints de l’AF. Lors de chaque visite annuelle, les procédures suivantes sont effectuées : des évaluations cardiaques, y compris l’ECG, des échocardiogrammes et la surveillance Holtor, un examen neurologique détaillé, une évaluation de la qualité de vie et du bien-être, ainsi que des des analyses de sang pour le dépistage des complications de l’AF comme le diabète.</p><h2>Sources de renseignements</h2><p>Pour plus d’informations sur l’AF, veuillez visitez les sites Web suivants :</p><p> <strong> <u>Canada</u></strong></p><p>Dystrophie musculaire Canada<br><a href="http://muscle.ca/fr/">www.muscle.ca</a></p><p>Ataxie Canada<br><a href="https://lacaf.org/fr/">www.lacaf.org</a></p><p> <strong> <u>International</u></strong></p><p>Friedreich's Ataxia Research Alliance (FARA)<br><a href="https://www.curefa.org/">www.curefa.org</a></p><p>euro-ataxia (European Federation of Hereditary Ataxias)<br><a href="http://www.euro-ataxia.org/">www.euro-ataxia.org</a></p><p>Muscular Dystrophy Association (MDA)<br><a href="http://www.mdausa.org/">www.mdausa.org</a></p><p>National Ataxia Foundation<br><a href="http://www.ataxia.org/">www.ataxia.org</a></p><h2>Références</h2><p>National Institute of Neurological Disorders and Stroke (2018, June). <em>Friedreich's Ataxia Fact Sheet</em>. Extrait du site Web <a href="https://www.ninds.nih.gov/Disorders/Patient-Caregiver-Education/Fact-Sheets/Friedreichs-Ataxia-Fact-Sheet#3070_3">https://www.ninds.nih.gov/Disorders/Patient-Caregiver-Education/Fact-Sheets/Friedreichs-Ataxia-Fact-Sheet#3070_3</a></p><p>National Organization for Rare Disorders (2018). <em>Rare Disease Database: Friedreich’s Ataxia</em>. Extrait du site Web <a href="https://rarediseases.org/rare-diseases/friedreichs-ataxia/">https://rarediseases.org/rare-diseases/friedreichs-ataxia/</a></p><p>Dystrophie musculaire Canada (2019). <em>Types de maladies neuromusculaires : Ataxie de Friedreich</em>. Extrait du site Web <a href="http://muscle.ca/fr/decouvrir-la-dystrophie-musculaire/types-de-maladies-neuromusculaires/">http://muscle.ca/fr/decouvrir-la-dystrophie-musculaire/types-de-maladies-neuromusculaires/</a></p><p>Ataxie Canada (Juin 2014). <em>Problèmes cardiaques dans l’ataxie de Friedreich</em>. Extrait du site Web <a href="https://lacaf.org/fr/problemes-cardiaques-ataxie-friedreich/">https://lacaf.org/fr/problemes-cardiaques-ataxie-friedreich/</a></p><p>Corben LA, Lynch D, Pandolfo M, et al (2014). Consensus clinical management guidelines for Friedreich ataxia. <em>Orphanet J Rare Dis, 9</em>: 184.</p>

 

 

 

 

Friedreich ataxia (FRDA)3848.00000000000Friedreich ataxia (FRDA)Friedreich ataxia (FRDA)FEnglishGenetics;NeurologyChild (0-12 years);Teen (13-18 years)BodyNervous system;Muscular systemConditions and diseasesAdult (19+) CaregiversNA2020-01-06T05:00:00ZGrace Yoon, MD, FRCPC9.6000000000000051.60000000000001865.00000000000Health (A-Z) - ConditionsHealth A-Z<p>Learn about the genetic neuromuscular disorder called Friedreich ataxia (FRDA).</p><h2>What is ataxia?</h2><p>Ataxia is a movement disorder. Movement disorders are conditions that cause involuntary body movements. Uncontrolled movement starts in the brain, in the area you use to move, speak and pay attention. When children have ataxia, they have trouble controlling their muscles and can be clumsy and awkward.</p><h2>What is Friedreich ataxia?</h2><p>Friedreich ataxia (FRDA) is an inherited condition that causes loss of muscle coordination (ataxia), slurred speech (dysarthria), weakness and sensory loss. Symptoms usually begin between ages five and 15, with most diagnoses made before age 25. Occasionally, symptoms begin in adults over 30 or in children younger than five years of age. Although it is a rare disorder, FRDA is the most common form of inherited childhood onset ataxia, occurring in about 1 in 40,000 people. In some regions or ethnic groups, this number might be a little higher or lower. The time that it takes for FRDA to progress happens at different speeds in different children and can eventually impair day-to-day life.</p><h2>Key points</h2><ul><li>FRDA is an inherited condition that causes slow, progressive loss of muscle coordination (ataxia), slurred speech (dysarthria), weakness and sensory loss. The rate of progression of FRDA varies from person to person.</li><li>Symptoms usually begin between ages five and 15, with most diagnoses made before age 25.</li><li>Many of the symptoms and accompanying complications can be treated to help individuals maintain optimal functioning for as long as possible.</li><li>FRDA is the most common form of inherited childhood-onset ataxia, occurring in about 1 in 40,000 people. In some regions or ethnic groups, this number might be a little higher or lower.</li><li>FRDA is caused by an alteration (mutation) in a gene called <em>FXN</em>. The <em>FXN</em> gene carries the instructions for making a protein called frataxin, which is necessary for the body to function properly.</li></ul><h2>Signs and symptoms of Friedreich ataxia</h2><p>Children with FRDA may show some or all of the following signs and symptoms:</p><ul><li>Curvature of the spine (<a href="/Article?contentid=2006&language=English">scoliosis</a>) and foot deformities (high arches in the feet called “pes cavus”)</li><li>Difficulty knowing where their hands and feet are in space (impaired position sense), leading to difficulties with balance and coordination</li><li>Weakness in the legs and hands</li><li>Mild to severe <a href="/Article?contentid=1576&language=English">heart problems</a>, such as thickening of the heart muscle (<a href="/Article?contentid=1629&language=English">cardiomyopathy</a>)</li><li>Hearing loss</li><li>Changes in vision</li><li>Problems with bladder control</li><li>Fatigue</li><li>Difficulty speaking</li><li><a href="/Article?contentid=1717&language=English">Diabetes</a></li></ul><h2>Friedreich ataxia is a genetic disease</h2> <figure><span class="asset-image-title">What are genes?</span><img src="https://assets.aboutkidshealth.ca/akhassets/What_is_a_gene_MED_ILL_EN.jpg" alt="A cell, chromosome, DNA strand, gene, and DNA building blocks (called nucleotides)" /><figcaption class="asset-image-caption">Genes are made of long strings of nucleotides on a section of DNA. Groups of genes are packed tightly in a chromosome.</figcaption> </figure> <p>FRDA is an inherited condition, meaning it is passed from parents to their children through genes. Genes are the instructions that our cells use to make proteins. They tell our cells how to work and what to do. For example, one gene may determine the colour of your hair or your blood type. Each person carries two copies of each gene. A child gets (inherits) one copy from their mother and the other from their father.</p><p>FRDA is caused by the mutation of a gene called <em>FXN</em>, which makes a protein called frataxin. Normally, people have two working copies of the <em>FXN</em> gene. Children with FRDA have two non-working copies.</p><p>FRDA occurs in a child only if both parents are carriers; that is, if both parents carry one normal (working) version of the <em>FXN</em> gene and one mutated (non-working) version of the <em>FXN</em> gene. FRDA is a recessive condition, which means that both parents have passed down their mutated <em>FXN</em> gene to their child.</p><p>Most parents do not know that they carry the mutated <em>FXN</em> gene because they have only one copy of it. This makes them carriers of FRDA. They are unaffected and do not have any symptoms of the condtition. In fact, most carriers are unaware of their carrier status until they have a child with FRDA. If both carrier parents pass the mutated <em>FXN</em> gene to their child, that child will have FRDA. In each pregnancy, carrier couples have a one-in-four chance of having a child with FRDA, a one-in-two chance of having a child who is a carrier of FRDA, and a one-in-four chance of having a child who is not a carrier of FRDA nor has the condition.</p> <figure class="asset-c-80"> <span class="asset-image-title">Inheritance pattern of Friedreich ataxia</span><img src="https://assets.aboutkidshealth.ca/AKHAssets/FriedreichAtaxia.jpg" alt="Inheritance pattern of two parents who are carriers of Friedreich ataxia, producing three possible combinations" /><figcaption class="asset-image-caption">Friedreich ataxia is caused by the mutation of a gene called <em>FXN</em>. The ‘R’ above represents the working <em>FXN</em> gene and the ‘r’ represents the recessive non-working <em>FXN</em> gene.</figcaption> </figure> <p>For more information about genes, please see the AboutKidsHealth section on <a href="https://www.aboutkidshealth.ca/body/interactive?module=genetics">How the Body Works: Genetics</a>.</p><h2>Diagnosis</h2><p>There are many types of mutations that can lead to genetic disorders. In the case of FRDA, the mutation comes from the addition of genetic material. The mutated <em>FXN</em> gene is much longer than the normal gene. A normal <em>FXN</em> gene contains a three base sequence (GAA) that is repeated five to 33 times in the DNA. These are the instructions for the body to produce the protein frataxin. The instructions for the mutated version of the <em>FXN</em> gene are much longer, and the sequence is repeated between 66 and 1700 times. This causes the gene to turn off, which stops the production of frataxin. Without frataxin, the nerves in the brain and spinal cord become damaged.</p><p>To confirm a diagnosis, children suspected of having FRDA can have a genetic blood test to determine whether or not they have the mutated gene. The test looks specifically at the <em>FXN</em> gene to determine if there is a mutation. Children with one normal <em>FXN</em> gene and 34 to 65 repeated sequences on the other gene are said to have a “premutation”. They do not show any symptoms of FRDA; however, there is an increased chance for the repeated sequence size to increase in their reproductive cells. This means that they are potential carriers of the disorder and could have a future child with FRDA. Children with 44 to 66 repeated sequences on one <em>FXN</em> gene may, develop FRDA later in life if the second copy of the gene is mutated.</p><p>In some cases, a child may have a different type of genetic mutation that also causes FRDA called a point mutation or “spelling mistake” in the <em>FXN</em> gene. Further testing may be needed if your child has this type of mutation.</p><p>Other tests that may help in the diagnosis of FRDA include the following:</p><ul><li>Electromyogram (EMG), a test for measuring the electrical activity of muscle cells</li><li> <a href="/Article?contentid=1283&language=English">Nerve conduction studies</a>, tests measuring the speed of impulses transmitted by nerves</li><li> <a href="/Article?contentid=1276&language=English">Electrocardiogram</a> (also called EKG or ECG), a test that measures the electrical activity of the heart</li><li> <a href="/Article?contentid=1274&language=English">Echocardiogram</a>, a test using sound waves to take pictures of the heart</li><li>Blood tests to check for elevated glucose levels and vitamin E levels</li><li> <a href="/Article?contentid=1270&language=English">Magnetic resonance imaging (MRI)</a> or <a href="/Article?contentid=1272&language=English">computed tomography (CT) scans</a>, tests that take pictures of the brain and spinal cord</li></ul><h3>Related conditions</h3><p>Some other conditions that can look like FRDA include: ataxia with vitamin E deficiency; abetalipoproteinemia, Refsum disease; infantile onset spinocerebellar ataxia; ataxia-telangiectasia; and many others. A geneticist can help to make a definitive diagnosis.</p><h2>Treatment</h2><p>There is currently no cure for FRDA, but there are symptom treatments that can help maintain optimal functioning for as long as possible. FRDA is managed by ensuring proper care is given to the systems of the body that can be affected by the condition. This includes regular follow-up with a neurologist, a cardiologist (to monitor for heart problems) and an endocrinologist (hormone specialist to monitor for diabetes). Children with scoliosis will also need to be monitored by an orthopedic surgeon. Some diabetes and heart complications can be managed with medications, and research suggests that taking antioxidants may also help with heart-related problems in FRDA.</p><p>Physiotherapy is recommended to help monitor and maintain range of motion, and to help design an appropriate exercise program. An occupational therapist can assist with alternative communication and walking aids, and they can also assess safety risks in the home.</p><p>These symptom treatments can help improve your child’s quality of life by reducing the severity of the complications associated with FRDA. To develop the best treatment plan for a child with FRDA, parents, doctors, teachers, therapists and other family members should work closely together in the best interest of the child.</p><h2>Complications</h2><p>FRDA is a progressive condition that breaks down the muscles and nerves of the body over time. It does not affect intelligence, and the rate of progression happens at different speeds in different children. Children with FRDA experience a loss of muscle coordination (ataxia) and feel off-balance when walking. They may have difficulty knowing where their hands and feet are in space, and may develop weakness in their legs and hands. Curvature of the spine (scoliosis), slurred speech, stiffness of the lower limbs, loss of joint sensation, loss of sensation in the legs and feet, and difficulty controlling bowel and bladder function may develop over time.</p><p>More than half of individuals with FRDA also have a heart condition called <a href="/Article?contentid=1629&language=English">hypertrophic cardiomyopathy</a>. This can be associated with an abnormal heart rhythm, so routine follow-up with a cardiologist is important. Some individuals with FRDA can develop diabetes, so regular screening through blood work is also important. Other features include vision changes and/or hearing loss.</p><h2>Genetic counselling</h2><p>Genetic counselling can help families adjust and cope with the stresses associated with having a child with FRDA. Prenatal testing can also be done during a pregnancy. If you or your child have tested positive for a mutation or have a family history of FRDA, you may want to talk to a <a href="/Article?contentid=1594&language=English">genetic counsellor</a>. A genetic counsellor will help interpret and review the genetic testing or options for prenatal diagnosis for future family planning.</p><h2>Support</h2><p>For some families, it is helpful to connect with others who are experiencing a similar medical condition. Before and after diagnosis, psychological counselling or participation in support groups is often beneficial for children with FRDA and their family members.</p><h2>At SickKids</h2><p>SickKids has a special multi-disciplinary clinic for children with FRDA and their families. The clinic takes place in the cardiology department, and it is staffed by a cardiologist, nurse practitioner, geneticist and genetic counsellor who have experience taking care of children with FRDA. Cardiac evaluations including EKG; echocardiograms and Holtor monitoring; a detailed neurological examination; assessment of quality of life and well-being; and bloodwork to screen for complications of FRDA, such as diabetes, are performed during each annual visit.</p><h2>Resources</h2><p>For more information on FRDA, visit the following websites:</p><p> <strong> <u>Canada</u></strong></p><p>Muscular Dystrophy Canada<br> <a href="http://www.muscle.ca/">www.muscle.ca</a></p><p>Ataxia Canada<br> <a href="https://lacaf.org/en/about-us-2/">www.lacaf.org</a></p><p> <strong> <u>International</u></strong></p><p>Friedreich's Ataxia Research Alliance (FARA)<br> <a href="https://www.curefa.org/">www.curefa.org</a></p><p>euro-ataxia (European Federation of Hereditary Ataxias)<br> <a href="http://www.euro-ataxia.org/">www.euro-ataxia.org</a></p><p>Muscular Dystrophy Association (MDA)<br> <a href="http://www.mdausa.org/">www.mdausa.org</a></p><p>National Ataxia Foundation<br> <a href="http://www.ataxia.org/">www.ataxia.org</a></p><h2>References</h2><p>National Institute of Neurological Disorders and Stroke (2018, June). <em>Friedreich's Ataxia Fact Sheet</em>. Retrieved from <a href="https://www.ninds.nih.gov/Disorders/Patient-Caregiver-Education/Fact-Sheets/Friedreichs-Ataxia-Fact-Sheet#3070_3">https://www.ninds.nih.gov/Disorders/Patient-Caregiver-Education/Fact-Sheets/Friedreichs-Ataxia-Fact-Sheet#3070_3</a></p><p>National Organization for Rare Disorders (2018). <em>Rare Disease Database: Friedreich’s Ataxia</em>. Retrieved from <a href="https://rarediseases.org/rare-diseases/friedreichs-ataxia/">https://rarediseases.org/rare-diseases/friedreichs-ataxia/</a></p><p>Muscular Dystrophy Canada (2019). <em>Types of Neuromuscular Disorders: Friedreich’s Ataxia</em>. Retreived from <a href="http://muscle.ca/discover-md/types-of-neuromuscular-disorders/">http://www.muscle.ca/about-muscular-dystrophy/types-of-neuromuscular-disorders/</a></p><p>Ataxia Canada (2014, June). <em>Cardiac problems in Friedreich’s Ataxia</em>. Retreived from <a href="https://lacaf.org/en/cardiac-problems-in-friedreich-ataxia/">https://lacaf.org/en/cardiac-problems-in-friedreich-ataxia/</a></p><p>Corben LA, Lynch D, Pandolfo M, et al (2014). Consensus clinical management guidelines for Friedreich ataxia. <em>Orphanet J Rare Dis, 9</em>: 184.</p>Friedreich ataxia (FRDA)False