Definition and Presentation
- CMD refers to a group of neuromuscular disorders manifesting as hypotonia and muscle weakness within the first 2 years of life, often from birth.
- Muscle biopsies typically show dystrophic abnormalities, and affected children may present with:
- Congenital joint contractures
- Central nervous system involvement, affecting the brain and/or eyes
- Elevated serum creatine kinase (CK), which may be markedly high.
Clinical Course
- CMD weakness is generally slowly progressive, though some children may have a static clinical course.
Advances in Classification
- CMD classification has shifted from structural abnormalities in the CNS to systems reflecting:
- Genetic mutations
- Muscle pathology
Diagnostic Tools
- Neonatal Presentation: Hypotonia and arthrogryposis.
- MRI Findings: Often abnormal, reflecting specific CMD conditions.
- Muscle Biopsy:
- Typical dystrophic changes
- Immunostaining to detect deficiencies (e.g., alpha-2 laminin or alpha-dystroglycan).
- Genetic Testing:
- Identifies specific mutations (though some cases suggest additional genetic heterogeneity).
Inheritance Patterns