Autosomal Recessive Juvenile Parkinsonism (AR-JP)
Autosomal Recessive Juvenile Parkinsonism (AR-JP), also known as PARK2 or PDJ, is a form of Parkinson’s disease (PD) that was initially described in Japan. It is one of the monogenic forms of PD, meaning it is caused by mutations in a single gene.
Genetics
AR-JP is caused by homozygous or compound heterozygous mutation in the parkin gene (PARK2) on chromosome 6q26. The parkin gene is one of the two genes that have been associated with autosomal recessive PD.
ymptoms
AR-JP is characterized by the cardinal signs of Parkinson disease (PD): bradykinesia, resting tremor, and rigidity. Bradykinesia refers to slowness of movement, resting tremor is a shaking or trembling of a body part when it is at rest, and rigidity is stiffness or inflexibility of the muscles.
The median age at onset is 31 years, but the disease can start anywhere between 3 and 81 years. Lower-limb dystonia, which is a movement disorder that causes involuntary muscle contractions, may be a presenting sign.
Progression and Treatment
The disease is slowly progressive, with disease duration of more than 50 years reported. Clinical findings vary, and hyperreflexia, which is overactive or overresponsive reflexes, is common. Cognitive decline appears to be no more frequent than in the general population.
AR-JP is characterized by a marked response to levodopa treatment. Levodopa is a common treatment for Parkinson’s disease that increases the level of dopamine in the brain. However, levodopa-induced dyskinesias, which are abnormal, uncontrolled, involuntary movements, frequently occur.
Conclusion
AR-JP is a rare form of Parkinson’s disease that is caused by mutations in the parkin gene. It is characterized by typical symptoms of Parkinson’s disease, such as bradykinesia, resting tremor, and rigidity. The disease is slowly progressive and responds well to levodopa treatment, although levodopa-induced dyskinesias frequently occur. Further research is needed to better understand the disease and develop more effective treatments.
