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Monozygotic twins with facioscapulohumeral dystrophy (FSHD): implications for genotype/phenotype correlation
R C Griggs1, R Tawil, M McDermott
1Department of Neurology, Wayne C. Gorell Molecular Biology Laboratory of the University of Rochester School of Medicine and Dentistry, Rochester, New York, USA.
Muscle & Nerve. Supplement
|April 12, 2013
Summary
Genetic factors primarily determine the onset and severity of facioscapulohumeral dystrophy (FSHD). While gene mutations dictate FSHD progression, other influences may affect muscle involvement asymmetry.
Area of Science:
- Genetics
- Neuromuscular Disorders
- Twin Studies
Background:
- Facioscapulohumeral dystrophy (FSHD) is an autosomal-dominant condition characterized by variable muscle weakness, onset age, and progression.
- Monozygotic twins offer a unique model to differentiate genetic from non-genetic influences on disease trajectory.
Purpose of the Study:
- To investigate the genetic and non-genetic factors influencing the phenotypic variability of facioscapulohumeral dystrophy (FSHD).
- To compare disease manifestation in monozygotic twins with FSHD to understand genetic versus environmental contributions.
Main Methods:
- Studied three sets of monozygotic twins with FSHD, including one discordant pair, using quantitative muscle function tests.
- Compared twin data with 59 other FSHD subjects to establish a reference population.
Main Results:
- Concordant monozygotic twins exhibited similar age of onset, disability, and muscle function, suggesting genetic determination.
- Significant asymmetry in specific muscle involvement was observed even in concordant twins, indicating non-genetic influences.
- One discordant twin set suggested a postzygotic mutation's role in FSHD development.
Conclusions:
- The primary gene lesion in FSHD appears to dictate disease onset and overall severity.
- Non-genetic factors likely contribute to the observed asymmetries in muscle involvement in facioscapulohumeral dystrophy.
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