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Genetic analysis of complement C1s deficiency associated with systemic lupus erythematosus highlights alternative

Mariane T Amano1, Virgínia P L Ferriani, Marlene P C Florido

  • 1Departamento de Imunologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, Av. Prof. Lineu Prestes 1730, CEP 05508-900 São Paulo, SP, Brazil.

Molecular Immunology
|December 8, 2007
PubMed

Insights

Complement C1s deficiency is linked to autoimmune diseases like lupus. This study identifies a new C1s mutation causing deficiency in a family, revealing insights into complement system regulation and disease development.

Area of Science:

  • Immunology
  • Genetics
  • Molecular Biology

Background:

  • Deficiencies in classical complement pathway proteins are associated with autoimmune diseases.
  • C1s deficiency often co-occurs with C1r deficiency, with a notable link to systemic lupus erythematosus (SLE).

Observation:

  • A family with four C1s-deficient children, two of whom developed SLE, was studied.
  • Classical complement pathway activation was absent in the children's sera, while alternative and lectin pathways were functional.
  • Reduced C1s levels were found in parents, and C1r levels were lower in all affected family members compared to controls.

Findings:

  • All four siblings were homozygous for a C1s cDNA mutation (c.938X) causing a premature stop codon, leading to undetectable C1s.
  • Impaired C1s synthesis was confirmed in patient fibroblasts.
  • Previously uncharacterized C1s mRNA splice variants, involving exon 3 skipping and alternative splicing in intron 1, were identified in normal human cells.

Implications:

  • This research elucidates the genetic basis of C1s deficiency and its role in SLE pathogenesis.
  • The discovery of novel C1s splice variants broadens our understanding of complement system regulation.
  • Findings contribute to the diagnosis and potential therapeutic strategies for complement deficiencies and associated autoimmune disorders.

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