# NM_000064.4(C3):c.2669C>G (p.Pro890Arg)

https://sugi.bio/variant/c3-p-pro890arg

## Summary

**C3 p.Pro890Arg (c.2669C>G)** is classified **Uncertain significance** in C3 (ClinVar, Multiple submitters, 2 submitters; last evaluated 2025-10-05). AlphaMissense: likely benign (0.1729); Very rare (popmax 0.00802%, afr).

**At a glance:** Uncertain significance · review: Multiple submitters · rsID rs753876258 · 2 submitters · AlphaMissense likely benign · very rare (popmax 0.00802%, afr)

## For patients & families {#patients}

This is a change in the C3 gene that is currently of uncertain significance — a definitive interpretation has not yet been established, submitted by 2 submitters.

*Reference information, not medical advice, and not a prediction for any individual. A genetic counselor or clinician can interpret what it means for you and your family.*

**Support & next steps:** [Find a genetic counselor (NSGC)](https://findageneticcounselor.nsgc.org/).

## Identity {#identity}

| Field | Value |
| --- | --- |
| Gene | [C3](https://sugi.bio/atlas/gene/C3/) |
| Protein change (HGVS p.) | p.Pro890Arg |
| Coding change (HGVS c.) | c.2669C>G |
| MANE Select transcript | [NM_000064](https://www.ncbi.nlm.nih.gov/nuccore/NM_000064) |
| dbSNP | [rs753876258](https://www.ncbi.nlm.nih.gov/snp/rs753876258/) |
| Variant type | single nucleotide variant |
| Location | chr19:6697471-6697471 (GRCh38) |
| ClinVar | [VCV1502901](https://www.ncbi.nlm.nih.gov/clinvar/variation/1502901/) |

**All HGVS expressions:** `LRG_27:g.28181C>G`, `NC_000019.10:g.6697471G>C`, `NC_000019.9:g.6697482G>C`, `NG_009557.1:g.28181C>G`, `NM_000064.4:c.2669C>G`

## Computational & population evidence {#evidence}

**Concordance:** Mixed / partial computational evidence (see below).

- AlphaMissense **likely benign** (0.1729)
- REVEL 0.049 (moderately benign-leaning) — agrees with AlphaMissense
- SaProt LLR -10.983 (damaging) — differs from AlphaMissense
- → **In-silico consensus:** SaProt calls this damaging; AlphaMissense and REVEL do not
- Conservation: phyloP 5.097, GERP -1.84, phastCons 1 — highly conserved (differs from AlphaMissense)
- CADD: **PHRED 12.01**. No single ClinGen-calibrated threshold exists and the expert panels that use CADD disagree — GUCY2D/AIPL1 require ≥ 20.0 for an untranslated-region variant, ABCA4 ≥ 28.1 for a synonymous or indel variant, the Pulmonary Hypertension panel imports Pejaver 2022's missense-calibrated numbers, and the Antibody Deficiencies panel declines CADD entirely for PIK3CD. CADD v1.7 also incorporates Zoonomia phyloP, so it partly re-expresses the conservation above. *Descriptive; no threshold applied.*
- Regional missense constraint: **o/e 0.74** across the covering region of the MANE Select transcript (6,684,600–6,719,350), spanning 34,750 bp. Chi-square p 3.5e-28. Describes the region, not this allele; gnomAD v4.1.1's own constrained determination. *Descriptive; no ACMG code applied.*
- SpliceAI: **not assessed** — no allele at this position is in our SpliceAI release, either because it lies outside the scored MANE transcript scope or because every allele is below Δ0.2. We cannot tell which, so this claims neither; absence is not evidence against a splicing effect.
- Population frequency (gnomAD v4.1): grpmax **0.00802%** (afr) · FAF95 0.00347% · FAF99 0.00229% · 6/74,830 in the highest group · 22/1,613,828 alleles overall — very rare (popmax 0.00802%, afr).

| Ancestry group | Allele frequency | 1 in |
| --- | --- | --- |
| African / African-American (grpmax) | 0.00802% | 12,472 |
| East Asian | 0.00668% | 14,962 |
| Admixed American | 0.00334% | 29,982 |
| European (non-Finnish) | 0.000932% | 107,272 |

*Computational predictors are not independent (ClinGen Variant Classification guidance): AlphaMissense (Cheng et al. 2023) carries the ACMG weight for missense and conservation (phyloP/GERP/phastCons) for non-missense; REVEL (Pejaver-2022 calibrated strength bands) and SaProt (Su et al. 2023, structure-aware, ClinVar-independent protein language model, raw LLR) are shown as orthogonal agreement signals, not additive. For frequency, the gnomAD v4.1 grpmax filtering allele frequency (FAF95) is ClinGen's designated BA1/BS1 input (gnomAD v4 guidance v3.0, June 2025); BA1/BS1 thresholds are disease-specific, not a blanket 5%. Predictions, not a clinical determination.*

## Gene constraint & dosage {#gene-context}

**C3** population constraint: LOEUF 0.541, pLI 1.2692e-06, missense-Z 4.4464. *Lower LOEUF and higher pLI indicate a gene that tolerates loss-of-function poorly; ClinGen dosage is the curated haploinsufficiency call.*

Curated gene–disease validity (ClinGen):

- **C3 glomerulonephritis** — Moderate (AD)
- **atypical hemolytic-uremic syndrome with C3 anomaly** — Definitive (AD)

## Protein context {#protein}

Residue **890** lies in a disulfide bond.

AlphaFold model confidence (whole protein): pLDDT 79.84, 23% of residues very-high.

**80 experimental structure(s)** (PDB): [11MG](https://www.rcsb.org/structure/11MG), [11MH](https://www.rcsb.org/structure/11MH), [1C3D](https://www.rcsb.org/structure/1C3D), [1GHQ](https://www.rcsb.org/structure/1GHQ), [1W2S](https://www.rcsb.org/structure/1W2S), [2A73](https://www.rcsb.org/structure/2A73) — incl. mutant structure 3RJ3.

## What this gene does {#gene-function}

*Describes the biological roles of C3 (the gene this variant disrupts) — not effects measured for this specific variant. A damaging variant is expected to affect these functions and pathways; the degree depends on the variant.*

**How this variant is thought to act:** C3's established molecular role includes C5L2 anaphylatoxin chemotactic receptor binding. In Reactome, C3 is annotated in disease pathway(s) including **Purinergic signaling in leishmaniasis infection**.

**Disease mechanism (Reactome):** C3 loss or alteration is curated in [Purinergic signaling in leishmaniasis infection](https://reactome.org/content/detail/R-HSA-9660826).

### Pathways affected {#pathways}

C3 participates in **11 Reactome pathways** (⚕ = disease pathway):

| Pathway (Reactome) | Evidence |
| --- | --- |
| ⚕ [Purinergic signaling in leishmaniasis infection](https://reactome.org/content/detail/R-HSA-9660826) | curated |
| [Activation of C3 and C5](https://reactome.org/content/detail/R-HSA-174577) | curated |
| [Alternative complement activation](https://reactome.org/content/detail/R-HSA-173736) | curated |
| [G alpha (i) signalling events](https://reactome.org/content/detail/R-HSA-418594) | curated |
| [Immunoregulatory interactions between a Lymphoid and a non-Lymphoid cell](https://reactome.org/content/detail/R-HSA-198933) | curated |
| [Neutrophil degranulation](https://reactome.org/content/detail/R-HSA-6798695) | curated |
| [Peptide ligand-binding receptors](https://reactome.org/content/detail/R-HSA-375276) | curated |
| [Post-translational protein phosphorylation](https://reactome.org/content/detail/R-HSA-8957275) | curated |
| [Regulation of Complement cascade](https://reactome.org/content/detail/R-HSA-977606) | curated |
| [Regulation of Insulin-like Growth Factor (IGF) transport and uptake by Insulin-like Growth Factor Binding Proteins (IGFBPs)](https://reactome.org/content/detail/R-HSA-381426) | curated |
| [Affinity selection of immunoglobulins](https://reactome.org/content/detail/R-HSA-9938027) | electronic |

### Molecular function & processes (GO — experimentally supported) {#go}

**Molecular function:** C5L2 anaphylatoxin chemotactic receptor binding, receptor ligand activity.

**Biological process:** positive regulation of protein phosphorylation, complement activation, positive regulation of vascular endothelial growth factor production, positive regulation of D-glucose transmembrane transport, regulation of triglyceride biosynthetic process, positive regulation of lipid storage.

## Clinical significance {#significance}

**Uncertain significance** — review status Multiple submitters *(criteria provided, multiple submitters, no conflicts)*, last evaluated 2025-10-05.

**Submitter consensus:** unanimous (2/2 Uncertain significance).

**Submission history:** 2 submissions (2023–2025); classifications have been stable.

### Submitter classifications {#submitters}

| Submitter | Classification | Review | Method | Date |
| --- | --- | --- | --- | --- |
| Mayo Clinic Laboratories, Mayo Clinic | Uncertain significance | criteria provided, single submitter | clinical testing | 2023-03-16 |
| Labcorp Genetics (formerly Invitae), Labcorp | Uncertain significance | criteria provided, single submitter | clinical testing | 2025-10-05 |

**Reported phenotype names (ClinVar):** not provided, none provided.

## Similar variants {#similar}

Related C3 variant pages (same residue, condition, or type): [C3 p.Pro890His](/variant/c3-p-pro890his), [C3 p.Pro890Ser](/variant/c3-p-pro890ser), [C3 p.Pro890Leu](/variant/c3-p-pro890leu), [C3 p.Pro890=](/variant/c3-p-pro890), [C3 c.1003+1G>A](/variant/c3-c-1003-plus-1g-a), [C3 c.2863+1G>T](/variant/c3-c-2863-plus-1g-t), [C3 c.4030-2A>G](/variant/c3-c-4030-minus-2a-g), [C3 p.Arg161Trp](/variant/c3-p-arg161trp).

### Data sources & attribution {#sources}

ClinVar (NCBI — public domain, built 2026-10-11); gnomAD v4.1 (Broad Institute, built 2026-10-06); AlphaMissense (Cheng et al. 2023, © Google DeepMind — CC BY 4.0, built 2026-01-27); REVEL (Ioannidis et al. 2016 — ODbL, built 2026-07-13); SaProt (Su et al. 2023 — MIT, built 2026-07-14); SpliceAI (Illumina — free for non-commercial use, built 2026-10-13); CADD (Rentzsch et al. 2019, University of Washington — free for non-commercial use, built 2026-10-10); Conservation (phyloP/phastCons/GERP) (UCSC hg38 470-way mammal (Hiller Lab) + Ensembl Compara, built 2026-07-12); gnomAD Non-coding Constraint (Gnocchi) (Chen et al. 2024, Broad Institute — CC0, built 2026-10-11); gnomAD Regional Missense Constraint (Broad Institute — CC0, built 2026-10-13); Pangolin (Zeng & Li 2022 — CC BY 4.0, built 2026-10-11); Repeat regions (UCSC — RepeatMasker, TRF, segmental duplications, built 2026-10-11); ClinGen (ClinGen, built 2026-09-22); UniProt (CC BY 4.0); Reactome / GO (CC BY 4.0, built 2026-09-23); MaveDB (per-record license, built 2026-10-11); CIViC (CC0, built 2026-09-22); Orphanet (Orphanet, built 2026-06-12)

*Primary record: NCBI ClinVar (variation 1502901). Classifications reflect these databases as of the page's build date and may change. Free reference use — not medical advice; consult the primary submitters and a clinician.*