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Absence of dystrophin in two patients with Becker type Xp21 muscular dystrophy
T Mongini1, L Palmucci, C Doriguzzi
1Paolo Peirolo Centre for Neuromuscular Diseases, University of Turin, Italy.
Abstract:
Two patients with Xp21 muscular dystrophy Becker type showed absence of dystrophin in muscle biopsy tested with 4 antibodies (polyclonal anti-60 kDa, monoclonal against the rod domain, the C-terminus and the N-terminus). DNA analysis did not detect any deletion in one patient and demonstrated deletion of exons 3-7 in the other. The cases represent an exception to the strict correlation between the dystrophin pattern in muscle biopsy and the clinical course of the disease: in fact both the patients are still walking at 14 and 15 years respectively. The possibility of similar cases must be considered not only in the prognosis of Xp21 muscular dystrophy but the more so in the evaluation of therapeutical trials.
Insights
Two Becker muscular dystrophy patients lacked dystrophin but retained ambulation, challenging typical disease progression correlations. These findings impact prognosis and therapeutic trial evaluations for Xp21 muscular dystrophy.
Area of Science:
- Neurology
- Genetics
- Biochemistry
Background:
- Becker muscular dystrophy (BMD) is an X-linked neuromuscular disorder typically characterized by reduced dystrophin protein.
- Muscle biopsy and DNA analysis are standard diagnostic tools for identifying dystrophin abnormalities and gene deletions.
Observation:
- Two patients with Xp21 muscular dystrophy Becker type presented with a complete absence of dystrophin in muscle tissue.
- Immunohistochemical analysis using four different antibodies confirmed the lack of dystrophin.
- Genetic analysis revealed no deletion in one patient and a deletion of exons 3-7 in the other.
Findings:
- The observed dystrophin absence contradicts the expected severe phenotype in Becker muscular dystrophy.
- Despite the lack of dystrophin, both patients maintained ambulation at 14 and 15 years of age.
- These cases highlight a dissociation between muscle biopsy findings and clinical presentation.
Implications:
- The findings challenge the established correlation between dystrophin levels and clinical severity in Becker muscular dystrophy.
- This necessitates re-evaluation of prognostic models for Xp21 muscular dystrophy.
- Consideration of such atypical cases is crucial for the accurate assessment of therapeutic interventions in clinical trials.