Which complement deficiency will 90% of patients develop SLE?

The development of systemic lupus erythematosus (SLE) is strongly associated with deficiencies in the complement system, particularly due to the role of the complement components in clearing immune complexes and modulating immune responses. Among the options provided, a deficiency in C1q, C1r, or C1s leads to a significantly increased risk of developing SLE.

C1q is a crucial component of the classical complement pathway and plays a vital role in initiating the complement cascade, which is involved in the clearance of apoptotic cells and immune complexes. When C1q function is deficient, there is impaired clearance of these complexes, which can lead to excessive immune activation and autoantibody production—hallmarks of SLE. In fact, studies have demonstrated that approximately 90% of individuals with C1q deficiency will develop SLE, making it a particularly relevant deficiency in the context of this autoimmune disease.

Other complement deficiencies, like those in C2 and C4, are also associated with an increased risk of SLE, but the prevalence is not as high as that seen with C1q deficiency. C3 deficiency can lead to a variety of infections due to its role in opsonization and inflammation, but it is not specifically tied