label: C2 Deficiency
label_lc: c2 deficiency
description: Lack of production of functional C2 protein, due to a genetic defect. It is the most common genetic complement deficiency. Ten percent of C2 deficient patient will develop systemic lupus erythematosus at an early age. Patients also present with frequent sinopulmonary infections often with Streptococcus pneumoniae.