Parkinsonian phenotype in Machado-Joseph disease (MJD/SCA3): a two-case report.
BACKGROUND
Machado-Joseph disease (MJD), or spinocerebellar ataxia type 3 (SCA3), is an autosomal dominant neurodegenerative disorder of late onset, which is caused by a CAG repeat expansion in the coding region of the ATXN3 gene. This disease presents clinical heterogeneity, which cannot be completely explained by the size of the repeat tract. MJD presents extrapyramidal motor signs, namely parkinsonism, more frequently than the other subtypes of autosomal dominant cerebellar ataxias. Although parkinsonism seems to segregate within MJD families, only a few MJD patients develop parkinsonian features and, therefore, the clinical and genetic aspects of these rare presentations remain poorly investigated. The main goal of this work was to describe two MJD patients displaying the parkinsonian triad (tremor, bradykinesia and rigidity), namely on what concerns genetic variation in Parkinson's disease (PD) associated loci (PARK2, LRRK2, PINK1, DJ-1, SNCA, MAPT, APOE, and mtDNA tRNA(Gln) T4336C).


METHODS
Patient 1 is a 40 year-old female (onset at 30 years of age), initially with a pure parkinsonian phenotype (similar to the phenotype previously reported for her mother). Patient 2 is a 38 year-old male (onset at 33 years of age), presenting an ataxic phenotype with parkinsonian features (not seen either in other affected siblings or in his father). Both patients presented an expanded ATXN3 allele with 72 CAG repeats. No PD mutations were found in the analyzed loci. However, allelic variants previously associated with PD were observed in DJ-1 and APOE genes, for both patients.


CONCLUSIONS
The present report adds clinical and genetic information on this particular and rare MJD presentation, and raises the hypothesis that DJ-1 and APOE polymorphisms may confer susceptibility to the parkinsonian phenotype in MJD.
Center of Research in Natural Resources, University of the Azores, Ponta Delgada, Portugal. mcbettencourt@uac.pt
Conceição
C
Bettencourt
Cristina
C
Santos
Paula
P
Coutinho
Patrizia
P
Rizzu
João
J
Vasconcelos
Teresa
T
Kay
Teresa
T
Cymbron
Mafalda
M
Raposo
Peter
P
Heutink
Manuela
M
Lima
D000328:Adult; D000483:Alleles; D001057:Apolipoproteins E / Q000235:genetics; D000067699:Ataxin-3; D005260:Female; D020022:Genetic Predisposition to Disease / Q000235:genetics; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics; D017827:Machado-Joseph Disease / Q000150:complications / Q000175:diagnosis* / Q000235:genetics*; D008297:Male; D009154:Mutation; D009419:Nerve Tissue Proteins / Q000235:genetics*; D009687:Nuclear Proteins / Q000235:genetics*; D015513:Oncogene Proteins / Q000235:genetics; D020734:Parkinsonian Disorders / Q000150:complications / Q000235:genetics*; D010641:Phenotype; D011110:Polymorphism, Genetic / Q000235:genetics; D000071617:Protein Deglycase DJ-1; D012091:Repetitive Sequences, Nucleic Acid / Q000235:genetics; D012097:Repressor Proteins / Q000235:genetics*
D001057:Apolipoproteins E; D047908:Intracellular Signaling Peptides and Proteins; D009419:Nerve Tissue Proteins; D009687:Nuclear Proteins; D015513:Oncogene Proteins; D012097:Repressor Proteins; C105131:PARK7 protein, human; D000071617:Protein Deglycase DJ-1; C092341:ATXN3 protein, human; D000067699:Ataxin-3