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Intermediate CAG repeat lengths (53,54) for MJD/SCA3 are associated with an abnormal phenotype.
N van Alfen1, R J Sinke, M J Zwarts
1Department of Neurology, University Medical Center, Nijmegen, The Netherlands.
Annals of Neurology
|June 21, 2001
Summary
Intermediate repeat lengths in Machado-Joseph Disease/Spinocerebellar Ataxia (MJD/SCA3) can be pathogenic. This finding suggests a link between these genetic variations and the development of restless legs syndrome and peripheral nerve disorders.
Area of Science:
- Genetics
- Neurology
- Molecular Biology
Background:
- Machado-Joseph Disease/Spinocerebellar Ataxia (MJD/SCA3) is a neurodegenerative disorder.
- The disease is typically associated with expanded CAG repeat lengths in the ATXN3 gene.
- Intermediate repeat lengths are often considered non-pathogenic or of uncertain significance.
Purpose of the Study:
- To investigate the clinical manifestations of Machado-Joseph Disease/Spinocerebellar Ataxia (MJD/SCA3) in a Dutch family with intermediate repeat lengths.
- To determine if intermediate repeat lengths can be pathogenic and associated with specific neurological symptoms.
Main Methods:
- Genetic analysis of the ATXN3 gene to determine repeat lengths.
- Clinical neurological examinations of affected family members.
- Assessment for symptoms of restless legs syndrome and peripheral neuropathy.
Main Results:
- Four family members across two generations presented with intermediate repeat lengths (53 and 54) for MJD/SCA3.
- Three affected individuals exhibited restless legs syndrome, fasciculations, and sensorimotor axonal polyneuropathy.
- Central neurological abnormalities were observed in only two members.
Conclusions:
- This family study demonstrates that intermediate repeat lengths for MJD/SCA3 can be pathogenic.
- Intermediate repeat lengths may predispose individuals to developing restless legs syndrome and peripheral nerve disorders.