The first case of Schwartz-Jampel syndrome (SJS) or chondrodystrophic myotonia was explained in 1962 by Oscar Schwartz and Robert S. Jampel in siblings with myotonic myopathy and blepharophimosis.

Classification:

• Type 1A: Recognized in childhood, moderate bone dysplasia.
• Type 1B: Similar to 1A, but manifests at birth with more prominent bone dysplasia.
• Type 2: Most severe, high neonatal mortality, also known as Stuve-Wiedemann syndrome, associated with LIFR gene mutation on chromosome 5p13.

Clinical Features

• Common Characteristics:9-year-old boy with Schwartz-Jampel syndrome (Source: Basiri et al., (2015))

  • Short stature: 90%
  • Clinical myotonia: 85%
  • Puckered-small mouth: 80%
  • Muscle hypertrophy: 70%
  • Fixed facies: 55%
  • Bone abnormalities: 45%
  • Raised muscle enzymes: 45%
  • Hip dysplasias: 40%
  • Blepharophimosis and blepharospasm: 32.5%

• Skeletal Features:

  • Spinal deformities
  • Fragmenting of femoral epiphysis
  • Widened metaphysis
  • Joint contractures
  • Osteoporosis
  • Delayed bone age

• Less Common Features:

  • High pitched voice
  • Bilateral carpal tunnel syndromes
  • Malignant hyperthermia
• Diagnostic Findings:

• Normal/slightly elevated creatine kinase and aldolase
• Normal nerve conduction studies
• Electromyography: Continuous muscle activity, high frequency repetitive potentials, myotonic discharges.
• Muscle biopsy: Nonspecific myopathic changes
• Spinal X-rays: Kyphosis and other skeletal deformities

Genetic Basis

• Inheritance: Autosomal recessive, reports of dominant inheritance.
• Mutation: HSPG2 gene on chromosome 1p34-36.1.
• Protein Affected: Perlecan, a component of basement membranes, cartilage, and bone marrow stromal cells.

Diagnosis

• Characteristic Triad: Facial dysmorphism, skeletal deformities, myotonic discharges.
• Differential Diagnosis:
  • Cramp and stiffness (Stiff person syndrome, Isaac's syndrome)
  • Myotonic disorders (Congenital myotonic dystrophy, myotonic dystrophy, myotonia congenita, paramyotonia congenital)
  • Muscular dystrophies (Becker dystrophy, Duchenne dystrophy, congenital muscular dystrophy)
  • Congenital myopathies
  • Channelopathies
  • Mucopolysaccharidosis (Morquio's syndrome)
  • Ehlers-Danlos Syndrome
  • Malignant hyperthermia
  • Blepharospasm
  • Stuve-Wiedemann syndrome

Treatment

• Symptomatic Management:

  • Decrease abnormal muscle activity causing stiffness and cramping.
  • Medications:
    • Anticonvulsants: Carbamazepine, Phenytoin
    • Antiarrhythmic drugs: Mexiletine, Procainamide
  • Non-Pharmacologic Modalities:
    • Physiotherapy
    • Warming
    • Massage
    • Warming-up prior to exercise
    • Gradual stretching

• Surgical Interventions:

  • Myectomy
  • Levator resection
  • Lateral canthopexy for blepharospasm and eyelid anomalies

• Botulinum Toxin-A: Alternative treatment for blepharospasm, considered instead of surgical options (Suphatsathienkul P et al., 2024).

Conclusion

• Diagnostic Specificity: The triad of “myotonia, facial dysmorphism, and skeletal deformities” is highly specific for diagnosing SJS in children.
• Confirmative Testing: DNA testing for HSPG2 gene mutations on chromosome 1p34-36.1.

References

• Basiri K, Fatehi F, Katirji B (2015) The Schwartz-Jampel syndrome: Case report and review of literature. Adv Biomed Res 4 ():163. DOI: 10.4103/2277-9175.162538 PMID: 26436077.
• National Center for Biotechnology Information (NCBI). Schwartz-Jampel syndrome (Concept ID: C0036391). MedGen. Available at: https://www.ncbi.nlm.nih.gov/medgen/19892. Accessed [8 June 2024].
• Suphatsathienkul P, Sakpichaisakul K, Wechapinan T, Trachoo O, Virawan S, Wanitphakdeedecha R (2024) Successful Treatment of Schwartz-Jampel Syndrome with Botulinum Toxin Type A. Dermatol Ther (Heidelb) 14 (2):545-556. DOI: 10.1007/s13555-023-01088-7 PMID: 38285320.