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Relationship between trinucleotide repeat expansion and phenotypic variation in Huntington's disease
R G Snell1, J C MacMillan, J P Cheadle
1Institute of Medical Genetics, University of Wales College of Medicine, Heath Park, Cardiff, UK.
Nature Genetics
|August 1, 1993
Summary
Huntington's disease (HD) CAG repeat length impacts age of onset. Larger repeats on the HD gene and normal paternal alleles correlate with earlier onset, influencing disease progression and genetic factors.
Area of Science:
- Genetics
- Neurodegenerative Diseases
- Molecular Biology
Background:
- Huntington's disease (HD) is a neurodegenerative disorder characterized by the expansion of CAG repeats in the HTT gene.
- The number of CAG repeats is known to correlate with disease onset and severity.
Purpose of the Study:
- To investigate the relationship between CAG repeat length in the Huntington's disease gene and age at onset.
- To explore the influence of normal paternal alleles on age at onset in maternally transmitted HD.
Main Methods:
- Molecular analysis of CAG repeat sequences in the Huntington's disease gene.
- Statistical correlation analysis between repeat numbers and age at onset in patients and controls.
Main Results:
- CAG repeat ranges were 30-70 in patients and 9-34 in controls.
- Significant negative correlations were found between HD chromosome repeat number and age at onset.
- A negative correlation was observed between normal paternal allele repeats and age at onset in maternally transmitted HD.
Conclusions:
- CAG repeat length is a key determinant of age at onset in Huntington's disease.
- Normal paternal allele repeat size influences age at onset, suggesting a role for normal gene function variation.
- Sex-specific effects and normal allele size contribute to variability in Huntington's disease onset.