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Transcript of Machado-Joseph disease
Machado-Joseph disease is a movement disorder.
It was first discovered in the 1970s.
It is a rare hereditary ataxia, which is a general term for lack of muscle control.
MJD is inherited as autosomal dominant.
It is the most common autosomal dominant spinocerebellar ataxia. Origin The name Machado-Joseph disease comes from two families of Portuguese/Azorean descent who were among the first families described with the unique symptoms of the disease.
The name Machado comes from William Machado, a native of an island in the Portuguese Azores.
The name Joseph comes from Antone Joseph, a Portuguese sailor with the defective gene who migrated to California in 1845. Types of MJD
MJD has been subclassified into 3 types, which are distinguished by the age of onset and range of symptoms. Types of MJD
Typical age of onset between 10 and 30 years.
Characterized by severe dystonia.
Dystonia - sustained muscle contractions that cause: Twisting of the body and limbs, Repetitive movements, Abnormal postures, Rigidity. Type II Type III
Onset between 40-70 years of age.
Has a relatively slow rate of progression.
Is often characterized by:
Muscle atrophy in the arms and legs
Uncoordinated gait that may cause stumbling or falling.
Unpleasant sensations Genetics
MJD belongs to a class of genetic disorders called triplet repeat diseases.
The gene is located on the long arm of chromosome 14q32; is capable of producing mutated protein called ataxin-3.
The mutant gene has an increased number of “CAG” repeats, which can range from 40 to more than 200.
The result in an unstable, expanded, disease-casing allele. Begins between 20 and 50 years of age.
Has an intermediate rate of progression.
Common symptoms include: Spasticity, Spastic gait, Exaggerated reflex responses. More on Genetics Diagnosis
Recognizing and identifying the typical symptoms of the disease.
For patients that are FH positive, genetic testing is the most efficient and definitive way to make the diagnosis.
Genetic testing is also recommended for individuals with a family history of the disease but who do not show any symptoms. More On Genetics The mutant protein accumulates in affected cells and forms intra-nuclear inclusion bodies, which are insoluble spheres located in the nucleus of the cell.
The spheres interfere with the normal operation of the nucleus and cause the cell to degenerate and die.
The cell degeneration and death occurs in the hindbrain, which includes the cerebellum, brainstem, and upper spinal cord, thus leading to deficits in movement. Treatment MJD is incurable.
Antispasmodic drugs, such as baclofen, can help reduce spasticity.
Speech therapy can aide in the treatment of dysarthria and dysphagia.
Prism glasses can reduce blurry vision or double vision. More Treatments
Physiotherapy can help patients cope with
disability associated with gait problems.
Physical aids, such as walkers and wheelchairs, can be used to assist patients with everyday activities.
Medication can be used to treat other problems, such as sleep disturbances, cramps, and urinary dysfunction. This is in contrast to the 6 to 34 repeats in the wild-type allele.
The wild-type protein is located predominantly in the cytoplasm of cells.
In contrast, the mutant ataxin-3 protein is localized within the nucleus of neuronal cells. References More Diagnosis
Neuroimaging with MRI or CT scan often reveals cerebellar atrophy.
It is also important to rule out other causes of ataxia, including:
Space occupying lesions
Vascular events Franca MC, et al. Chronic Pain in Machado-Joseph Disease. A Frequent and Disabling Symptom. Arch Neurol. Vol 64 (No. 12), Dec 2007.
Horimoto, Y, et al. Brainstem in Machado-Joseph disease: atrophy or small size? European Journal of Neurology 2008, 15: 102-105.
Kieling C, Prestes PR, Saraiva-Pereira ML, Jardim LB. Survival estimates for patients with Machado-Joseph disease (SCA 3). Clin Genet 2007: 72: 543-545.
Machado Joseph Disease http://www.mazornet.com/genetics/machado.htm
National Institute of Neurological Disorders and Stroke. Machado-Joseph Disease Fact Sheet.
Opal P; Zoghbi HY. The spinocerebellar ataxias. UpToDate. 2007.