Complement factor 2 deficiency: a clinical and serological family study

D D'Cruz1, J Taylor, T Ahmed

  • 1Lupus Arthritis Research Unit, Rayne Institute, St Thomas's Hospital, London, United Kingdom.

Insights

Inherited complement factor 2 (C2) deficiency can lead to connective tissue diseases like cutaneous vasculitis and sicca syndrome. This family study highlights C2 deficiency

Area of Science:

  • Immunology
  • Genetics
  • Rheumatology

Background:

  • Inherited complement deficiencies are linked to various connective tissue diseases.
  • The complement system plays a crucial role in immune regulation and pathogen clearance.

Observation:

  • A family with inherited complement factor 2 (C2) deficiency was studied.
  • Two members with homozygous C2 deficiency presented with cutaneous vasculitis and sicca syndrome.
  • Other family members had heterozygous C2 deficiency and shared a specific HLA haplotype.

Findings:

  • Homozygous C2 deficiency was associated with autoimmune manifestations including vasculitis and sicca syndrome.
  • Heterozygous C2 deficiency was linked to the HLA-A25, B18, DR2 (w15) haplotype.
  • The mother with heterozygous C2 deficiency had seropositive rheumatoid arthritis.
  • Elevated levels of cryoglobulins, anti-endothelial cell antibodies, and anticardiolipin antibodies were detected.

Implications:

  • This study suggests a potential link between C2 deficiency and the development of specific autoimmune connective tissue diseases.
  • Understanding these genetic associations can aid in diagnosing and managing patients with complement deficiencies and related autoimmune conditions.
  • Further research is warranted to elucidate the precise mechanisms connecting C2 deficiency, HLA type, and autoimmune disease pathogenesis.

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