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Deficiency of the first component of human complement

K B Reid1

  • 1Department of Biochemistry, University of Oxford, UK.

Immunodeficiency Reviews
|January 1, 1989
PubMed

Insights

C1 deficiency, caused by low levels of C1q, C1r, or C1s proteins, impairs immune complex clearance, leading to disease susceptibility. Genetic C1 deficiencies are rare, with few cases reported in scientific literature.

Area of Science:

  • Immunology
  • Complement System Biology

Background:

  • C1 deficiency involves reduced levels of C1q, C1r, or C1s proteins, crucial components of the classical complement pathway.
  • This deficiency impairs the body's ability to manage immune complexes effectively.

Purpose of the Study:

  • To summarize the clinical manifestations and prevalence of C1 deficiency.
  • To highlight the association between C1 deficiency and increased susceptibility to infections and immune-complex-related diseases.

Main Methods:

  • Literature review of reported cases of C1q, C1r, and C1s deficiencies.
  • Analysis of clinical patterns and genetic data from published studies.

Main Results:

  • C1 deficiency leads to ineffective immune complex clearance, causing symptoms typical of immune-complex diseases.
  • Individuals with C1 deficiency exhibit a high susceptibility to recurrent bacterial infections.
  • Genetic C1 deficiencies are rare, with limited documented cases (14 for C1q, 6 for C1r/C1s).

Conclusions:

  • C1 deficiency significantly compromises immune function, increasing vulnerability to infections and autoimmune conditions.
  • The rarity of genetic C1 deficiencies underscores their status as uncommon but clinically significant disorders.

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