Project description:We report new clinical features of delayed motor development, hypotonia, and ataxia in two young children with mutations (R756H and D923N) in the ATP1A3 gene. In adults, mutations in ATP1A3 cause rapid-onset dystonia-Parkinsonism (RDP, DYT12) with abrupt onset of fixed dystonia. The parents and children were examined and videotaped, and samples were collected for mutation analysis. Case 1 presented with fluctuating spells of hypotonia, dysphagia, mutism, dystonia, and ataxia at 9 months. After three episodes of hypotonia, she developed ataxia, inability to speak or swallow, and eventual seizures. Case 2 presented with hypotonia at 14 months and pre-existing motor delay. At age 4 years, he had episodic slurred speech, followed by ataxia, drooling, and dysarthria. He remains mute. Both children had ATP1A3 gene mutations. To our knowledge, these are the earliest presentations of RDP, both with fluctuating features. Both children were initially misdiagnosed. RDP should be considered in children with discoordinated gait, and speech and swallowing difficulties.
Project description:Rapid-onset dystonia with parkinsonism (RDP) or DYT12 dystonia is a rare form of primary, generalized dystonia. Patients do not present with any symptoms until triggered by a physiological stressor. Within days, patients will show both dystonia and parkinsonism. Mutations resulting in a loss of function in the ATP1A3 gene have been identified as the cause of RDP. ATP1A3 encodes the ?3 subunit of the Na(+)/K(+)-ATPase, which is exclusively expressed in neurons and cardiac cells. We have previously created a line of mice harboring a point mutation of the Atp1a3 gene (mouse homolog of the human ATP1A3 gene) that results in a loss of function of the ?3 subunit. The Atp1a3 mutant mice showed hyperactivity, spatial learning and memory deficits, and increased locomotion induced by methamphetamine. However, the full spectrum of the motor phenotype has not been characterized in the mutant mice and it is not known whether triggers such as restraint stress affect the motor phenotype. Here, we characterized the motor phenotype in normal heterozygous Atp1a3 mutant mice and heterozygous Atp1a3 mutant mice that have been exposed to a restraint stress. We found that this type of trigger induced significant deficits in motor coordination and balance in the mutant mice, characteristic of other genotypic dystonia mouse models. Furthermore, stressed mutant mice also had a decreased thermal sensitivity and alterations in monoamine metabolism. These results suggest that the Atp1a3 mutant mouse models several characteristics of RDP and further analysis of this mouse model will provide great insight into pathogenesis of RDP.
Project description:Although dystonias are a common group of movement disorders, the mechanisms by which brain dysfunction results in dystonia are not understood. Rapid-onset Dystonia-Parkinsonism (RDP) is a hereditary dystonia caused by mutations in the ATP1A3 gene. Affected individuals can be free of symptoms for years, but rapidly develop persistent dystonia and Parkinsonism-like symptoms after a stressful experience. Using a mouse model, we found that an adverse interaction between the cerebellum and basal ganglia can account for the symptoms of these individuals. The primary instigator of dystonia was the cerebellum, whose aberrant activity altered basal ganglia function, which in turn caused dystonia. This adverse interaction between the cerebellum and basal ganglia was mediated through a di-synaptic thalamic pathway that, when severed, alleviated dystonia. Our results provide a unifying hypothesis for the involvement of cerebellum and basal ganglia in the generation of dystonia and suggest therapeutic strategies for the treatment of RDP.
Project description:Rapid-onset dystonia-parkinsonism (RDP) is a movement disorder associated with mutations in the ATP1A3 gene. Signs and symptoms of RDP commonly occur in adolescence or early adulthood and can be triggered by physical or psychological stress. Mutations in ATP1A3 are also associated with alternating hemiplegia of childhood (AHC). The neuropathologic substrate of these conditions is unknown. The central nervous system of four siblings, three affected by RDP and one asymptomatic, all carrying the I758S mutation in the ATP1A3 gene, was analyzed. This neuropathologic study is the first carried out in ATP1A3 mutation carriers, whether affected by RDP or AHC. Symptoms began in the third decade of life for two subjects and in the fifth for another. The present investigation aimed at identifying, in mutation carriers, anatomical areas potentially affected and contributing to RDP pathogenesis. Comorbid conditions, including cerebrovascular disease and Alzheimer disease, were evident in all subjects. We evaluated areas that may be relevant to RDP separately from those affected by the comorbid conditions. Anatomical areas identified as potential targets of I758S mutation were globus pallidus, subthalamic nucleus, red nucleus, inferior olivary nucleus, cerebellar Purkinje and granule cell layers, and dentate nucleus. Involvement of subcortical white matter tracts was also evident. Furthermore, in the spinal cord, a loss of dorsal column fibers was noted. This study has identified RDP-associated pathology in neuronal populations, which are part of complex motor and sensory loops. Their involvement would cause an interruption of cerebral and cerebellar connections which are essential for maintenance of motor control.
Project description:Mutations in the ATP1A3 gene (the ?-3 subunit of the Na+/K+ ATPase) are associated with rapid-onset dystonia-parkinsonism; alternating hemiplegia of childhood; and cerebellar ataxia, areflexia, pes cavus, optic atrophy, and sensorineural hearing loss (CAPOS syndrome). The authors report 3 cases with pleiotropic movement disorders, including a novel mutation in a patient who presented with ataxia and dysphagia. Case 1 had a history of attention deficit hyperactivity disorder and developed dysphagia, chorea, and limb dystonia after a febrile illness at age 12 years. Case 2 presented with limb dystonia at age 26 years and dysarthia and dysphagia after a febrile illness. Case 3 had a history of learning disability and developed progressive ataxia with cerebellar atrophy at age 20 years. In all cases, deleterious mutations were identified in ATP1A3. They illustrate wide phenotypic variability, including chorea and ataxia. New cases are likely to be diagnosed as knowledge about the phenotypic spectrum expands.
Project description:BACKGROUND:ATP1A3 mutations have now been recognized in infants and children presenting with a diverse group of neurological phenotypes, including Rapid-onset Dystonia-Parkinsonism (RDP), Alternating Hemiplegia of Childhood (AHC), and most recently, Cerebellar ataxia, Areflexia, Pes cavus, Optic atrophy, and Sensorineural hearing loss (CAPOS) syndrome. METHODS:Existing literature on ATP1A3-related disorders in the pediatric population were reviewed, with attention to clinical features and associated genotypes among those with RDP, AHC, or CAPOS syndrome phenotypes. RESULTS:While classically defined phenotypes associated with AHC, RDP, and CAPOS syndromes are distinct, common elements among ATP1A3-related neurological disorders include characteristic episodic neurological symptoms and signs that vary in severity, duration, and frequency of occurrence. Affected children typically present in the context of an acute onset of paroxysmal, episodic neurological symptoms ranging from oculomotor abnormalities, hypotonia, paralysis, dystonia, ataxia, seizure-like episodes, or encephalopathy. Neurodevelopmental delays or persistence of dystonia, chorea, or ataxia after resolution of an initial episode are common, providing important clues for diagnosis. CONCLUSIONS:The phenotypic spectrum of ATP1A3-related neurological disorders continues to expand beyond the distinct yet overlapping phenotypes in patients with AHC, RDP, and CAPOS syndromes. ATP1A3 mutation analysis is appropriate to consider in the diagnostic algorithm for any child presenting with episodic or fluctuating ataxia, weakness or dystonia whether they manifest persistence of neurological symptoms between episodes. Additional work is needed to better identify and classify affected patients and develop targeted treatment approaches.
Project description:BACKGROUND:Rapid-onset dystonia-parkinsonism (RDP) is a rare autosomal dominant disorder that is caused by mutations in the ATP1A3 gene and is characterized by an acute onset of asymmetric dystonia and parkinsonism. To date, fewer than 75 RDP cases have been reported worldwide. Clinical signs of pyramidal tract involvement have been reported in several RDP cases, and none of them included the Babinski sign. CASE PRESENTATION:We report a 24-year-old Chinese female with RDP who exhibited a strikingly asymmetric, predominantly dystonic movement disorder with a rostrocaudal gradient of involvement and parkinsonism. Physical examiniations revealed hyperactive reflexes, bilateral ankle clonus and positive Babinski sign in the right. DTI showed reduced white matter integrity of the corticospinal tract in the frontal lobe and subpontine plane. Genetic testing revealed a missense mutation of the ATP1A3-gene (E277K) in the patient. CONCLUSION:We suggest that pyramidal tract impairment could be involved in rapid-onset dystonia-parkinsonism and the pyramidal tract impairment in RDP needs to be differentiated from HSP.
Project description:A woman from Italy presented with dystonic leg symptoms at the age of 59. Rapid-onset dystonia-parkinsonism (RDP) was not suspected until 3 affected children (2 male, 1 female) with presentations consistent with the disorder were recognized.The mother and four of her children (3 with and 1 without dystonia) were evaluated with an extensive battery including standardized history questionnaire and rating scales. In addition, all four children had cognitive testing and three of the four children had psychiatric interviews.In this family, a T613M mutation in the ATP1A3 gene was confirmed, the most common mutation present in patients with RDP. The proband's limb dystonia was atypical of RDP, symptoms of the others affected included dysarthria, asymmetric limb dystonia, and dysphagia more consistent with RDP. The two sons developed dystonia-parkinsonism in adolescence after consuming large amounts of alcohol. All 3 of those with psychiatric interviews reached diagnosable thresholds for mood disorder (bipolar or dysthymia) and some form of anxiety disorder.The phenotype and age of onset is broader than previously reported in RDP, suggesting that it could be under-reported. Prior to this study, neuropsychologic symptoms associated with RDP were under-appreciated. Those patients who are at risk or suspected of having RDP should be cautioned to avoid excessive alcohol intake. Further study is needed to assess if the cognitive and psychiatric features are part of a broader RDP phenotype and this may have implications for future research into genetic susceptibility for psychiatric disease.