Selective complete Clq deficiency associated with systemic lupus erythematosus

Area of Science:

• Immunology
• Rheumatology
• Genetics

Background:

• Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by diverse clinical manifestations.
• Complement component 1q (Clq) deficiency is a rare genetic disorder associated with increased susceptibility to infections and autoimmune diseases.
• Isolated Clq deficiency is a specific form where only Clq is absent, unlike other complement deficiencies.

Observation:

• A 17-year-old female presented with seizures, fever, arthralgia, hair loss, oral ulceration, and skin rash.
• Clinical and laboratory findings met the preliminary criteria for SLE classification.
• Skin biopsy revealed immunoglobulin and C3 deposition at the dermal-epidermal junction.

Findings:

• The patient exhibited absent total serum hemolytic complement activity due to a complete and selective deficiency of Clq.
• No antibodies to DNA or low C3/C4 levels were detected.
• No circulating inhibitor of Clq activity was identified.

Implications:

• This case underscores the association between isolated Clq deficiency and SLE, particularly with recurrent infections.
• Investigating Clq levels may be crucial in the diagnosis and management of SLE patients with unusual presentations or frequent infections.
• Understanding the role of Clq in immune regulation can provide insights into SLE pathogenesis and potential therapeutic targets.