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Meningococcal disease in congenital absence of the fifth component of complement

H E Nielsen1, C Koch

  • 1Department of Infectious Diseases M, Rigshospitalet, Copenhagen, Denmark.

Insights

Two brothers with recurrent meningococcal infections had a complete C5 deficiency. This inherited C5 deficiency was transmitted as an autosomal codominant trait, impacting immune response.

Area of Science:

  • Immunology
  • Genetics
  • Infectious Diseases

Background:

  • Recurrent bacterial infections can indicate underlying immune system deficiencies.
  • Complement component 5 (C5) is crucial for the membrane attack complex formation and pathogen lysis.

Observation:

  • A family presented with two brothers experiencing meningococcal infections, one affected twice.
  • The parents of the affected brothers were first-degree cousins, suggesting a potential genetic link.

Findings:

  • Both brothers exhibited a complete, isolated deficiency in both antigenic and functional C5.
  • The parents displayed C5 levels at half the normal range, consistent with a heterozygous carrier state.

Implications:

  • The study suggests an inherited C5 deficiency as the cause of recurrent meningococcal disease in this family.
  • The pattern of inheritance is compatible with an autosomal codominant trait for C5 deficiency.
  • Understanding C5 deficiency aids in diagnosing and managing individuals with recurrent infections and compromised complement pathways.

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