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Inherited deficiency of the third component of complement associated with recurrent pyogenic infections, circulating
Insights
Three children with complete C3 deficiency experienced recurrent bacterial infections and skin vasculitis. Their family members had lower C3 levels but remained healthy, indicating C3
Area of Science:
- Immunology
- Genetics
- Pediatrics
Background:
- Complement component 3 (C3) is crucial for innate and adaptive immunity.
- Deficiencies in complement components can lead to increased susceptibility to infections.
- The role of selective C3 deficiency in human health requires further elucidation.
Observation:
- A family study identified three siblings with homozygous C3 deficiency (0/11 children).
- Parents and six siblings exhibited subnormal C3 levels but were asymptomatic.
- Patients presented with recurrent bacterial infections and maculopapular rash during illness.
Findings:
- Homozygous C3 deficiency was strongly associated with severe bacterial infections.
- Immune complexes and leukocytoclastic vasculitis were observed during infectious episodes in deficient individuals.
- Subnormal C3 levels in relatives did not correlate with significant clinical manifestations.
Implications:
- Selective C3 deficiency poses a significant risk for recurrent bacterial infections.
- C3 deficiency is linked to immune complex-mediated inflammatory conditions like vasculitis.
- This study highlights the critical role of C3 in immune system function and host defense.
Abstract:
A family is described in which 3/11 children showed a homozygous deficiency of C3, and both parents and six other children had subnormal levels of C3. The three children with selective C3 deficiency suffered repeatedly from bacterial infections, whereas the parents and the other siblings were clinically healthy. During infectious episodes the patients showed a maculopapular skin rash, and at such times immune complexes were present in the serum. Biopsy specimens of the skin lesions showed the picture of leukocytoclastic vasculitis.