label: complement component C1r/C1s deficiency
label_lc: complement component c1r/c1s deficiency
description: "Lack of production of either functional C1r or C1s protein, due to a genetic defect. Approximately 60% of patients with a C1r/C1s deficiency will develop a severe systemic lupus erythematosus at an early age. Patients also present with frequent sinopulmonary infections often with Streptococcus pneumoniae."