Related Experiment Videos
Hereditary complement (C9) deficiency associated with dermatomyositis
E Ichikawa1, J Furuta, Y Kawachi
1Department of Dermatology, Institute of Clinical Medicine, University of Tsukuba, 1-1-1 Tenno-dai, Tsukuba, Ibaraki 305-8575, Japan. eikoi@md.tsukuba.ac.jp
The British Journal of Dermatology
|May 22, 2001
Summary
This study reports a Japanese woman with dermatomyositis and a hereditary complement component 9 (C9) deficiency. It shows that dermatomyositis muscle lesions can occur even without the C5b-9 membrane attack complex formation.
Area of Science:
- Immunology
- Genetics
- Rheumatology
Background:
- Dermatomyositis is an idiopathic inflammatory myopathy.
- The complement system, particularly the terminal pathway involving C5b-9, plays a role in inflammatory processes.
Observation:
- A 28-year-old Japanese woman presented with facial erythema and progressive muscle weakness, consistent with dermatomyositis.
- She was found to have a hereditary deficiency of the ninth complement component (C9).
- Despite low serum hemolytic complement (CH50) levels, muscle biopsy confirmed inflammatory myopathy.
Findings:
- Genetic analysis revealed a nonsense mutation in the C9 gene, causing a total absence of C9.
- Prednisolone treatment improved dermatomyositis symptoms but did not alter CH50 levels.
- This indicates that C9 deficiency and the inability to form the C5b-9 membrane attack complex did not preclude the development of dermatomyositis.
Implications:
- This case highlights that dermatomyositis can manifest despite a complete defect in the complement terminal pathway.
- It suggests alternative or parallel inflammatory pathways may drive muscle damage in dermatomyositis.
- Understanding these pathways could lead to novel therapeutic strategies for complement-related inflammatory diseases.