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The shortest expanded allele of the MJD1 gene in a Chinese MJD kindred with autonomic dysfunction

Weihong Gu1, Huizi Ma, Kang Wang

  • 1National Laboratory of Medical Molecular Biology, Department of Biochemistry and Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Science and Peking Union Medical College, Beijing, PR China.

European Neurology
|August 19, 2004
PubMed

Insights

Machado-Joseph disease, a type of spinocerebellar ataxia, can manifest with autonomic dysfunction. This study identifies the shortest known causative allele (51 CAG repeats) in a Chinese family, expanding the disease

Area of Science:

  • Genetics
  • Neurology
  • Molecular Biology

Background:

  • Machado-Joseph disease (MJD), an autosomal dominant spinocerebellar ataxia, is linked to expanded CAG repeats in the MJD1 gene.
  • Intermediate CAG alleles are associated with atypical neurological presentations.

Observation:

  • A Chinese family presented with hereditary spinocerebellar ataxia, with the proband exhibiting autonomic dysfunction alongside typical MJD symptoms.
  • Genetic analysis confirmed MJD and identified the shortest known causative expanded allele with 51 CAG repeats in the proband.

Findings:

  • The 51-CAG-repeat expansion represents the shortest causative allele identified for Machado-Joseph disease.
  • This case demonstrates that MJD can present with a 51-CAG-repeat expansion, broadening the known spectrum of clinical manifestations.
  • Clinical pleomorphism and the 51-CAG-repeat allele contributed to the patient's phenotype.

Implications:

  • The findings suggest that the clinical spectrum of Machado-Joseph disease is wider than previously recognized.
  • The study highlights the role of modifier factors in modulating MJD phenotype, as evidenced by unaffected individuals with MJD in another family.
  • This research contributes to a deeper understanding of MJD's genetic basis and clinical variability.

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