Hereditary Heterozygous C2 Deficiency: Variable Clinical and Serological Manifestations Among Three Sisters

Area of Science:

• Immunology
• Genetics

Background:

• Inherited complement deficiencies are a rare but established cause of systemic lupus erythematosus (SLE).
• The complement system plays a crucial role in immune regulation and clearance of immune complexes.

Observation:

• A case study of three biological sisters with hereditary heterozygous C2 deficiency is presented.
• Two sisters are dizygotic twins, exhibiting varying clinical and serological manifestations of SLE.
• All three sisters presented with positive antinuclear antibodies (ANA) and antiphospholipid (APL) antibodies, alongside decreased C2 and C4 complement levels.

Findings:

• Familial heterozygous C2 deficiency can lead to diverse SLE phenotypes.
• The co-occurrence of antiphospholipid antibodies in all three affected sisters with C2 deficiency is a significant and rarely described association.
• Variable clinical presentations underscore the multifactorial etiology of SLE.

Implications:

• This case emphasizes the importance of considering complement deficiencies in the etiology of SLE, particularly in familial cases.
• The association with antiphospholipid antibodies warrants further investigation in patients with C2 deficiency.
• Understanding these genetic and serological variations can aid in personalized SLE management and risk assessment.