Clinical variability and characteristic autoantibody profile in primary C1q complement deficiency

Rheumatology (Oxford). 2007 Oct;46(10):1612-4. doi: 10.1093/rheumatology/kem207.


Objectives: C1q deficiency is a rare inherited defect in the early part of the complement cascade. In this report, we describe the varied clinical features of patients with this condition as well as the characteristic autoantibody profile.

Methods: A large Pakistani family with a high degree of consanguinity is described in which the father and five sons have C1q deficiency, all with different clinical manifestations.

Results: Clinical features of C1q deficiency can vary from almost no disease to fulminant bacterial infection and localized lupus-like skin, renal or CNS disease. Autoantibodies to ribonucleoproteins such as anti-Sm and Ro, but not dsDNA, were present.

Conclusions: Awareness of the spectrum of clinical disease, autoantibody profiles and tests required to confirm the diagnosis of C1q deficiency are important if this life-threatening immunodeficiency disease is to be managed correctly.

Publication types

  • Case Reports

MeSH terms

  • Adolescent
  • Adult
  • Angioedemas, Hereditary / immunology
  • Autoantibodies / blood*
  • Child
  • Complement C1q / deficiency*
  • Humans
  • Lupus Erythematosus, Discoid / immunology
  • Lupus Nephritis / immunology
  • Lupus Vasculitis, Central Nervous System / immunology
  • Magnetic Resonance Imaging
  • Male
  • Meningitis, Pneumococcal / immunology
  • Opportunistic Infections / immunology
  • Pedigree
  • Vasculitis / immunology
  • Vasculitis / pathology


  • Autoantibodies
  • Complement C1q