Complement component C1r/C1s deficiency- MedGen UID:
- 461624
- •Concept ID:
- C3150274
- •
- Disease or Syndrome
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.
Immunodeficiency due to MASP-2 deficiency- MedGen UID:
- 462435
- •Concept ID:
- C3151085
- •
- Disease or Syndrome
MASP2 deficiency, classically defined as MASP2 protein level of less than 100 ng/ml, occurs in about 4% of Caucasians and up to 18% of some African populations. Some MASP2-deficient individuals have increased risk of infection or autoimmune disease, but most are asymptomatic. MASP2 plays a role in activation of the lectin pathway of the complement system; deficiency may thus lead to defects in the complement system (summary by Thiel et al., 2007 and Sokolowska et al., 2015).
For a discussion of genetic heterogeneity of lectin complement activation pathway defects, see LCAPD1 (614372).