DJ-1 (PARK7) mutations are less frequent than Parkin (PARK2) mutations in early-onset Parkinson disease.
ABSTRACT Mutations in the Parkin gene (PARK2) are the most commonly identified cause of recessively inherited early-onset Parkinson disease (EOPD) but account for only a portion of cases. DJ-1 (PARK7) was recently reported as a second gene associated with recessively inherited PD with a homozygous exon deletion and a homozygous point mutation in two families.
To investigate the frequency of DJ-1 mutations, the authors performed mutational analysis of all six coding exons of DJ-1 in 100 EOPD patients. For the detection of exon rearrangements, the authors developed a quantitative duplex PCR assay. Denaturing high performance liquid chromatography analysis was used to screen for point mutations and small deletions. Further, Parkin analysis was performed as previously described.
The authors identified two carriers of single heterozygous loss-of-function DJ-1 mutations, including a heterozygous deletion of exons 5 to 7 and an 11-base pair deletion, removing the invariant donor splice site in intron 5. Interestingly, both DJ-1 mutations identified in this study were found in the heterozygous state only. The authors also detected a polymorphism (R98Q) in 1.5% of the chromosomes in both the patient and control group. In the same patient sample, 17 cases were detected with mutations in the Parkin gene.
Mutations in DJ-1 are less frequent than mutations in Parkin in EOPD patients but should be considered as a possible cause of EOPD. The effect of single heterozygous mutations in DJ-1 on the nigrostriatal system, as described for heterozygous changes in Parkin and PARK6, remains to be elucidated.
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ABSTRACT: Although Parkinson's disease (PD) was first described almost 200 years ago, it remains an incurable disease with a cause that is not fully understood. Nowadays it is known that disturbances in the structure of pathological proteins in PD can be caused by more than environmental and genetic factors. Despite numerous debates and controversies in the literature about the role of mutations in the SNCA and PRKN genes in the pathogenesis of PD, it is evident that these genes play a key role in maintaining dopamine (DA) neuronal homeostasis and that the dysfunction of this homeostasis is relevant to both familial (FPD) and sporadic (SPD) PD with different onset. In recent years, the importance of alphasynuclein (ASN) in the process of neurodegeneration and neuroprotective function of the Parkin is becoming better understood. Moreover, there have been an increasing number of recent reports indicating the importance of the interaction between these proteins and their encoding genes. Among others interactions, it is suggested that even heterozygous substitution in the PRKN gene in the presence of the variants +2/+2 or +2/+3 of NACP-Rep1 in the SNCA promoter, may increase the risk of PD manifestation, which is probably due to ineffective elimination of over-expressed ASN by the mutated Parkin protein. Finally, it seems that genetic testing may be an important part of diagnostics in patients with PD and may improve the prognostic process in the course of PD. However, only full knowledge of the mechanism of the interaction between the genes associated with the pathogenesis of PD is likely to help explain the currently unknown pathways of selective damage to dopaminergic neurons in the course of PD.Current Genomics 12/2013; 14(8):502-17. DOI:10.2174/1389202914666131210205839 · 2.87 Impact Factor
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ABSTRACT: The studies presented in this review attempt to describe the operative properties of the genes involved in generation of early and late onset of Parkinson's disease or Parkinson-like disorders and how mutation in these genes relate to onset of manganism. These include the genes α-synuclein, parkin, PINK1, DJ-1, ATP13A2, and SLC30A10 which are associated with early-onset of Parkinson's as well as those genes linked with late onset of the disorder which include, LRRK2 and VPS35. Since mutations in these genes and excess Mn potentially disrupt similar cellular processes within the basal ganglia, it is reasonable to hypothesize that the expressed symptoms of Parkinson's disease may overlap with that of manganese (Mn) toxicity. There appears to be four common processes linking the two disorders, as mutations in genes associated with Parkinsonism initiate similar adverse biological reactions acknowledged to stimulate Mn-induced dopaminergic cell death including; 1) disruption of mitochondrial function leading to oxidative stress, 2) abnormalities in vesicle processing, 3) altered proteasomal and lysosomal protein degradation, and 4) α-synuclein aggregation The mutual neurotoxic processes provoked by mutations in these genes in concert with the biological disturbances produced by Mn, most likely, act in synchrony to contribute to the severity, characteristics and onset of both disorders.NeuroToxicology 08/2014; 44. DOI:10.1016/j.neuro.2014.08.006 · 3.05 Impact Factor