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Congenital muscular dystrophy with abnormal radiographic myelin pattern
J D Cook1, G G Gascon, A Haider
1Department of Pediatrics, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia.
Insights
This study identifies a congenital muscular dystrophy (CMD) subtype with specific brain and muscle abnormalities. Researchers propose it represents a distinct allelic variant of a gene crucial for muscle, myelin, and brain development.
Area of Science:
- Neurology
- Genetics
- Pediatrics
Background:
- Congenital muscular dystrophy (CMD) encompasses a group of inherited disorders affecting muscle development and function.
- Existing CMD classifications include Fukuyama CMD, Walker-Warburg (cerebral-ocular CMD), and Santavuori (muscle-eye-brain CMD).
- A distinct homogeneous clinical syndrome in children suggests a potentially unclassified or related CMD phenotype.
Purpose of the Study:
- To characterize a homogeneous clinical syndrome observed in 11 children with congenital muscular dystrophy.
- To compare this syndrome with previously reported cases and established CMD phenotypes.
- To propose a genetic basis and classification for this CMD variant.
Main Methods:
- Clinical assessment of 11 affected children, detailing symptoms from birth, muscle weakness, reflexes, creatine kinase levels, and nerve conduction.
- Analysis of muscle biopsy findings and neuroimaging (brain MRI) for white-matter abnormalities.
- Comparison of the current cohort with 48 previously reported similar cases and established CMD subtypes.
Main Results:
- The 11 children presented with consistent symptoms: neonatal weakness, slow improvement, generalized muscle weakness, areflexia, elevated creatine kinase, normal nerve conduction, dystrophic muscle changes, and specific periventricular white-matter abnormalities.
- This syndrome was designated as altered myelin radiographic pattern congenital muscular dystrophy (CMD), equivalent to occidental CMD.
- Phenotypic comparison suggested a relationship to Fukuyama CMD, Walker-Warburg CMD, and Santavuori CMD.
Conclusions:
- The identified syndrome represents a distinct phenotype of congenital muscular dystrophy, characterized by specific neurological and muscular features.
- Researchers propose that this phenotype, along with other recognized CMDs, may result from allelic variations of a single gene.
- This gene likely plays a critical role in regulating structural proteins essential for muscle integrity, myelination, and cortical development, explaining the observed phenotypic diversity.
Abstract:
We report 11 children with a homogeneous clinical syndrome affecting both sexes, characterized by weakness at birth, slowly improving course, weakness of all muscle groups, arreflexia, elevated blood creatine kinase, normal nerve conduction velocity, dystrophic changes on muscle biopsy, and diffuse periventricular cortical white-matter abnormalities with sparing of corpus callosum, internal capsule, and brain stem. We compare them to 48 other previously reported similar cases and designate them as altered myelin radiographic pattern congenital muscular dystrophy (CMD), which is the same as occidental CMD. We compare them to the other presently accepted phenotypes: progressive Fukuyama CMD, Walker-Warburg or cerebral-ocular CMD, and Santavuori or muscle-eye-brain CMD. We suggest that the different phenotypes are alleles of the same gene, which regulates or expresses a structural protein required for muscle integrity, myelination, and formation of the cortex. Such phenotypic diversity has been established for mutations of Xp21 in X-linked muscular dystrophies.