ImmunoDeficiency Resource (IDR)

C2 deficiency is one of the most common inherited complement component deficiency. It may occur in asymptomatic individuals but it is frequently associated with autoimmune manifestations, particularly with discoid or systemic lupus erythematosus. Approximately 40% of the patients with C2 deficiency develop SLE or discoid lupus and aproximately 50% develop recurrent infections. Patients with C2 deficiency express many of the characteristic features of lupus, but severe nephritis, cerebritis, and aggressive arthritis are less common than in complement sufficient SLE patients. Cutaneous lesions are common in C2 deficiencient patients with lupus, and many have a characteristic annular photosensitive rash. C2 deficiency patients have also other reumathic disordes as glomerulonephritis, dermatomyositis, anaphylactoid purpura, and vasculitis. The bacterial infections are usually systemic infections (e.g. sepsis and meningitis) with encapsulated organisms (Pneumococcus and H.influenzae) and more common in childhood.