The majority of people that have Parkinson disease appear to be random cases, but new studies have shown that specific genetic defects may increase the chances of developing Parkinson disease. Ten “Parkinson Disease Genes” have been identified, but only three specific genes have been found to be directly related to causing Parkinson disease. Recent investigations in familial-linked Parkinson disease have found that mutations in α-synuclein, parkin and DJ-1 have been clearly linked to Parkinson disease.
The mutation in the α-synuclein gene was first found in the Contursi ancestry and later found in several Greek ancestries. Through recent haplotype analyses it was found that they both share a common ancestor. Mutations in the α-synuclein gene are known to be a rare cause of Parkinson disease but evidence still shows that it exists. Individuals affected with α-synuclein mutations are known to have typical idiopathic Parkinson disease.
A mutation in the parkin gene has been discovered to cause Autosomal Recessive Juvenile Parkinsonism (AR-JP). Additionally, linkage and mutation analysis has shown the parkin gene to be influential in early-onset Parkinson disease. The discovery of a microdeletion in a family with AR-JP led to the identification of an AR-JP gene and named parkin. Linkage analysis was performed 13 families with AR-JP and researchers were able to map the location of the parkin gene to chromosome 6q25.2-27. Parkin mutations are now widely considered to be one of the major causes of familial Parkinson disease.
Researchers used a Real Time PCR (Polymerase Chain Reaction) strategy to identify a deletion of exons in the DJ-1 gene in a Dutch family. A similar mutation was found in the same gene in an Italian family. The fact that the DJ-1 gene was absent in the Dutch family and was inactive in the Italian family proved that a mutation in this gene causes Parkinson disease through a loss of function. Further studies are being done in order to...
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