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Parkin Type of Early-Onset Parkinson Disease.

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GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2017.
2001 Apr 17 [updated 2013 Apr 4].

Author information

1
Institute of Neurogenetics and Department of Neurology, University of Luebeck, Luebeck, Germany

Excerpt

CLINICAL CHARACTERISTICS:

Parkin type of early-onset Parkinson disease is characterized by rigidity, bradykinesia, and resting tremor. Lower-limb dystonia may be a presenting sign. Onset usually occurs between ages 20 and 40 years with an average age of onset in the early to mid-thirties. The disease is slowly progressive and disease duration of more than 50 years has been reported. Clinical signs vary; hyperreflexia is common. Dyskinesia as a result of treatment with levodopa frequently occurs.

DIAGNOSIS/TESTING:

The diagnosis of parkin type of early-onset Parkinson disease is considered primarily in individuals with early-onset parkinsonism (age <40 years), particularly if autosomal recessive inheritance is suspected. PRKN (formerly PARK2), the gene encoding the protein parkin, is the only gene in which pathogenic variants are known to cause parkin type of early-onset Parkinson disease. The diagnosis of parkin type of early-onset Parkinson disease can only be confirmed when pathogenic variants are identified on both alleles of PRKN (i.e., the individual is homozygous for the same pathogenic allele or compound heterozygous for two different pathogenic alleles). The variant detection frequency varies by family history and age of onset.

MANAGEMENT:

Treatment of manifestations: Levodopa and other dopaminergic agonists; deep brain stimulation (DBS) for those experiencing difficulty with levodopa therapy. Prevention of secondary complications: Do not use levodopa therapy above the dose needed for satisfactory clinical response. Surveillance: Neurologic follow-up including assessment of treatment every six to 12 months. Agents/circumstances to avoid: Neuroleptic treatment may exacerbate parkinsonism.

GENETIC COUNSELING:

Parkin type of early-onset Parkinson disease is inherited in an autosomal recessive manner. At conception, each sib of a proband has a 25% chance of being affected, a 50% chance of being a carrier, and a 25% chance of being unaffected and not a carrier. Each unaffected sib has a 2/3 chance of being a carrier. Carrier testing and prenatal testing for pregnancies at increased risk are possible if both pathogenic alleles have been identified in an affected family member.

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