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Different phenotypic expression in monozygotic twins with Huntington disease
M H Anca1, E Gazit, R Loewenthal
1Movement Disorder Unit, Department of Neurology, Tel-Aviv Sourasky Medical Center, 6 Weizmann Street, Tel-Aviv 64239, Israel.
American Journal of Medical Genetics. Part A
|December 18, 2003
Summary
Identical twins with Huntington disease (HD) showed different disease onset and symptoms. This suggests postzygotic genetic events may influence HD
Area of Science:
- Genetics
- Neuroscience
- Medical Research
Background:
- Huntington disease (HD) is a progressive neurodegenerative disorder.
- Genetic mutations are the primary cause of HD.
- The clinical presentation of HD typically varies among affected individuals.
Purpose of the Study:
- To report a unique case of monozygotic twins with Huntington disease.
- To investigate the influence of genetic identity on disease phenotype and onset.
- To explore potential explanations for phenotypic discordance in genetically identical individuals.
Main Methods:
- Clinical case study of 46-year-old identical male twins.
- Detailed comparison of disease onset, progression, motor symptoms, and behavioral changes.
- Genetic analysis to confirm monozygosity and presence of the HD mutation.
Main Results:
- Both twins carried the same Huntington disease mutation but presented with different ages of onset (32 vs. 35 years).
- Twin 1 exhibited chorea, dysarthria, and depression, progressing to severe disability.
- Twin 2 displayed gait disturbances, aggressive behavior, hypokinesia, rigidity, and dysarthria.
Conclusions:
- This is the first report of genetic identity with differing onset age and distinct motor/behavioral phenotypes in Huntington disease.
- Postzygotic genetic events are proposed as a likely explanation for the observed phenotypic variability.
- Further research into epigenetic factors and somatic mutations is warranted to understand HD pathogenesis.