complement component 3 deficiency
Findings
No curated finding names complement component 3 deficiency yet. Everything below is reference data from Mondo, HPO and GenCC, not evidence about what affects it.
Definition
A rare genetic disorder with an autosomal recessive pattern of inheritance. It is caused by the ineffective or decreased biosynthesis of the third complement component, C3. C3 deficiency may also be acquired acutely post-infection or chronically from co-morbid autoimmune disorders. If C3 is adequately synthesized, its rapid depletion may result in a functional deficiency. Clinical signs of the inherited deficiency present within the first decade of life and are consistent with the signs of recurrent systemic infection or immune complex disease. Deficiency of serum C3 and its major cleavage product, C3b, will decrease the effective humoral immune response to encapsulated bacteria. Deficiency of C3 also impairs clearance of circulating immune complexes and therefore predisposes to rheumatic and renal disease.
Definition from the Mondo Disease Ontology (MONDO:0013417), read 2026-09-29. CC BY 4.0.
- Inheritance
- Autosomal recessive inheritance
- Onset and course
- Infantile onset · Childhood onset
HPO, annotations 2026-09-02
Features
7 features
What the disease is reported to present with, and how often among people who have it — never how often a feature means the disease. HPO, annotations 2026-09-02.
- Decreased circulating complement C3 concentrationHPOHP:0005421
- 2 of 2 reported patients
- Recurrent bacterial infectionsHPOHP:0002718
- 1 of 1 reported patient
- Recurrent feverHPOHP:0001954
- 1 of 1 reported patient
- Recurrent pneumoniaHPOHP:0006532
- 2 of 2 reported patients
- Recurrent tonsillitisHPOHP:0011110
- 1 of 1 reported patient
- Systemic lupus erythematosusHPO
Genes
1 gene
Germline variants in the gene encoding each protein, as classified by GenCC submitters, each in their own words. Limited, disputed and refuted submissions are listed too.
- C3HGNC:1318
- Definitive · Laboratory for Molecular Medicine · Autosomal recessive · 2020
- Strong · Labcorp Genetics (formerly Invitae) · Autosomal recessive · 2021
- Supportive · Orphanet · Autosomal recessive · 2021
Where it sits
Other names
3 names
Resolves to: complement component 3 deficiency
- Also called
- C3 classic complement early component deficiencyC3 deficiencyclassic complement early component deficiency caused by mutation in C3