Type IV Machado Joseph Disease (MJD), also known as Spinocerebellar Ataxia Type 3 (SCA3), is a rare and progressive hereditary neurological disorder characterized by a variety of symptoms primarily affecting movement and coordination. It is classified as the most common form of autosomal dominant cerebellar ataxia, a group of genetic disorders that result in the degeneration of certain areas of the brain.
Individuals with Type IV MJD typically experience a wide range of symptoms, including muscle weakness and wasting, problems with balance and coordination, speech impairments, involuntary eye movements, and difficulty swallowing. The disease progresses gradually over time, leading to increasing disability and requiring the use of walking aids or wheelchairs in advanced stages.
Type IV MJD is caused by an abnormal expansion of a repeated genetic sequence within the Ataxin-3 gene. This leads to the production of a mutant protein that forms harmful aggregates in the affected brain areas. The age of onset varies, usually occurring in adulthood, although earlier onset forms are possible. The severity of symptoms can also vary, even among affected individuals within the same family.
Currently, there is no cure for Type IV MJD, and treatment is focused on managing symptoms and providing support to improve quality of life. This may include physiotherapy, speech therapy, occupational therapy, and assistive devices. Genetic counseling is also important for individuals and families at risk of inheriting the disease, as it can help in understanding recurrence risks and making informed decisions about family planning.
