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Schwartz-Jampel syndrome: clinical, electromyographic and genetic studies
B Ishpekova1, M Rasheva, M Moskov
1University Hospital, Department of Neurology, Sofia.
Insights
This study describes two sisters with chondrodystrophic myotonia, a rare genetic disorder characterized by muscle stiffness and weakness from infancy. Early diagnosis and understanding of this condition are crucial for managing its progressive symptoms.
Area of Science:
- Genetics and Molecular Biology
- Neurology
- Pediatrics
Background:
- Chondrodystrophic myotonia is a rare congenital disorder affecting muscle function.
- Understanding its genetic basis and clinical manifestations is essential for early diagnosis and management.
Observation:
- Two sisters from a consanguineous family presented with early-onset myotonia and progressive muscular weakness.
- Clinical features included facial dysmorphism, joint contractures, kyphoscoliosis, and abnormal muscle electrical activity on EMG.
- Electromyography (EMG) revealed spontaneous, high-frequency, low-voltage electrical discharges with a myotonic pattern in limb muscles.
Findings:
- The affected sisters exhibited severe symptoms including inability to walk, joint deformities, and characteristic facial features.
- Muscle enzyme levels were slightly elevated, and EMG confirmed myotonia, while nerve conduction studies were normal.
- The absence of symptoms in parents and other relatives suggests a recessive inheritance pattern.
Implications:
- The findings support the diagnosis of chondrodystrophic myotonia, highlighting its severe phenotype in affected individuals.
- This case underscores the importance of comprehensive clinical and electrophysiological evaluation for diagnosing rare myotonic disorders.
- Further research into the genetic underpinnings of chondrodystrophic myotonia could lead to improved diagnostic tools and therapeutic strategies.
Abstract:
Two sisters aged 9 and 7 from consanguineous parents are described. Both of them develop myotonia, muscular weakness as early as the first year after birth. At the age 3-4 a disturbed gait appeared due to knee joint contractures and limited joint movements. The children display facial dysmorphism (a small forehead, a flat base of the nose, a receding chin, an irregular order of the teeth, low-set ears, a high-arched palate, low hair-line), kyphoscoliosis, pigeon breast, severe contractures of the knee and elbow joint and foot deformities. The elder sister cannot walk. Hirsutism of all four limbs is found as well as sparse subcutaneous tissue. Muscles are stiff and firm. Tendon reflexes of the lower limbs are absent. Muscle enzymes show slightly increased values. The EMG needle examination in both sisters was abnormal. Spontaneous, continuous, high-frequency, low-voltage electrical discharges were observed in all distal and proximal muscles of the hands and legs. Some of them have a typical myotonic pattern. The MCV and the SCV was within the normal range. Both parents of our patients, their sister aged 4, as well as their grandparents showed no clinical and EMG abnormalities. All these data allow authors to affirm the diagnosis chondrodystrophic myotonia.
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