Complement 3 (C3) Deficiency
Complement 3 (C3) Deficiency. Autosomal recessive. Observed in 4 of 266 breeds tested in the Sniff Atlas, with measured carrier frequencies drawn from 242,663 dogs (Donner 2023). Per-dog phenotype outcome depends on penetrance, modifiers, and environment; the carrier frequencies below describe variant prevalence, not disease incidence.
- OMIA identifier
- OMIA:000155-9615
- InheritanceInheritance patternWhat it isHow the condition is passed down: recessive (two copies needed), dominant (one copy), or more complex.For your dogRecessive means a single-copy carrier is usually healthy but can still pass it on.PreciselyThe documented mode of Mendelian transmission (autosomal recessive or dominant, X-linked, etc.) per OMIA.OMIA · documented
- Autosomal recessive
- Source dataset
- Sniff Atlas v1.0.1 / DOI
A model of human complement component 3 deficiency
This is the canine counterpart of complement component 3 deficiency in people. That makes affected dogs a naturally-occurring model of the human disease, and it is part of why studying dogs moves medicine forward for everyone. It does not mean your dog has the human disease. It means the two share an underlying biology.
In people, the disease is described as: 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.
In humans it is also called: C3 classic complement early component deficiency, C3 deficiency, C3d.
Mapped from OMIA via the human disease's OMIM entry to the Mondo Disease Ontology (Monarch Initiative, CC-BY 4.0). Sniff renders this as a model-of link; the canine disease remains the subject of this page.
From OMIA's curated record
Documented in OMIA (Online Mendelian Inheritance in Animals). This describes the disease as recorded in the published literature, not a prediction for any individual dog. As of 2026-06-03.
Summary
Molecular genetics
Human analog
OMIA links this condition to its human counterpart in OMIM (Mendelian Inheritance in Man), the place to read across to the deeper human literature for the same biology.
Source: OMIA (Nicholas, Tammen & the Sydney Informatics Hub), entry OMIA:000155-9615, doi:10.25910/2AMR-PV70 (CC-BY 4.0).
How it presents
Catalogued in the Mondo disease ontology (the cross-species disease identity used by the Monarch Initiative) as complement component 3 deficiency (MONDO:0013417).
Phenotype terms: Human Phenotype Ontology + Mammalian Phenotype Ontology; disease terms: Mondo (Monarch Initiative). Cross-references curated by OMIA (doi:10.25910/2AMR-PV70, CC-BY 4.0).
Published references
The peer-reviewed papers behind this disease, curated by OMIA. Starred entries are OMIA-designated landmark papers. Showing 6 of 19.
- Complement C3 in Bernese Mountain dogs. · Vet Clin Pathol · 2010 · PMID 20003027
- Immunofluorescence staining for the detection of immunoglobulins and complement (C3) in dogs with renal disease. · Vet Rec · 2008 · PMID 19060316
- Serum concentrations of the third component of complement in healthy dogs and dogs with protein-losing nephropathy. · Am J Vet Res · 2006 · PMID 16817728
- Complement C3 deficiency: human, animal, and experimental models. · Pathobiology · 1994 · PMID 8031472
- Hereditary deficiency of C3 in animals and humans. · Int Rev Immunol · 1993 · PMID 8340676
References curated by OMIA (Nicholas, Tammen & the Sydney Informatics Hub), doi:10.25910/2AMR-PV70 (CC-BY 4.0). Full list at the OMIA entry.
Set each parent's status for Complement 3 (C3) Deficiency and see the odds for their puppies. Single recessive variant, exact Mendelian math.
These are the genetic odds for one known variant, not a promise: a real litter varies around them, and penetrance or other genes can change whether the condition ever appears. Use it to avoid pairing two carriers and to keep a line healthy, not to engineer a dog. Inheritance mode per OMIA.
See what Complement 3 (C3) Deficiency looks like in your dog's breed.
Top 4 well-sampled breeds (n ≥ 50)
Maximum carrier frequencyCarrier frequencyWhat it isHow many dogs in a breed carry one copy of a disease variant, usually without being affected themselves.For your dogA carrier is typically healthy. For most recessive conditions a dog needs two copies to be at risk.PreciselyThe proportion of a population carrying at least one copy of the variant allele. Population prevalence, not disease incidence.Sniff Atlas (Donner 2023) · measured per breed across variants in the Donner 2023 cohort, with Wilson 95% confidence intervalsWilson 95% confidence intervalWhat it isThe range the true frequency is probably in. A wide range means we are less sure, usually because few dogs were tested.For your dogTrust tight ranges; treat wide ones as rough estimates.PreciselyA binomial-proportion confidence interval (Wilson score, 95%) that stays reliable at small sample sizes.Sniff Atlas methodology · statistical. The list below is split into well-sampled breeds (n ≥ 50 tested) and small-sample breeds (n < 50, where the Wilson CI typically spans more than 20 percentage points and frequencies should not be compared directly to the well-sampled entries). Frequencies are population-level, not per-litter or per-line.
▸ Full table with Wilson 95% confidence intervals
| Breed | Carrier frequency | n tested |
|---|---|---|
| Brittany | 0.14% | 349 |
| Maltese | <0.1% | 2,413 |
| Labrador Retriever | <0.1% | 16,856 |
| American Staffordshire Terrier | <0.1% | 42,793 |
262 additional breeds in the Donner 2023 cohort were tested but showed no carriers.
Scope
This record carries the breed-level carrier frequencies from the Donner 2023 cohort. Penetrance data (the fraction of at-risk dogs that develop the phenotype) is not yet quantified for this disease in the Sniff Atlas v1.0.1. The OMIA entry is the authoritative reference for the clinical phenotype, inheritance pattern, and gene assignment.
Predicted disease relevance at the per-dog level is UNPROVEN. The carrier frequency is measured; phenotype outcome depends on penetrance, environment, and modifier loci. Consult a veterinarian for clinical interpretation.
Citations
If you use this record in published work, cite the Sniff Atlas (the published dataset that carries the breed-level carrier frequencies) and the upstream sources:
- Sniff Atlas v1.0.1 for the per-breed carrier frequencies:
Gehring, M. (2026). Sniff Atlas v1.0.1. Zenodo. https://doi.org/10.5281/zenodo.20566358. CC-BY 4.0.
- OMIA for the disease definition, inheritance, and gene assignment:
Nicholas, F. W., & Tammen, I. (2024). OMIA. Sydney Informatics Hub, The University of Sydney. https://doi.org/10.25910/2AMR-PV70. Entry: OMIA:000155-9615.
- Donner et al. 2023 for the breed × variant carrier-frequency cohort:
Donner, J., Freyer, J., Davison, S., Anderson, H., Blades, M., Honkanen, L., et al. (2023). Genetic prevalence and clinical relevance of canine Mendelian disease variants in over one million dogs. PLOS Genetics, 19(2), e1010651. https://doi.org/10.1371/journal.pgen.1010651.
Full citation formats (BibTeX, RIS, CITATION.cff) at sniff.world/cite.
Related
- Sniff Atlas v1.0.1, the source dataset for these frequencies.
- Browse breeds, per-breed Mendelian profiles, including this disease in context.
- OMIA entry OMIA:000155-9615, authoritative clinical reference.
- About OMIA, the catalogue this record comes from, and how Sniff uses it.