# NM_001710.6(CFB):c.2058_2061del (p.Ser687fs)

https://sugi.bio/variant/cfb-p-ser687fs

## Summary

**CFB p.Ser687fs (c.2058_2061del)** is classified **Uncertain significance** in CFB (ClinVar, Single submitter, 1 submitter; last evaluated 2025-09-26). Very rare (popmax 0.000254%, nfe); Associated with atypical hemolytic-uremic syndrome.

**At a glance:** Uncertain significance · review: Single submitter · 1 submitter · 1 linked condition · very rare (popmax 0.000254%, nfe)

## For patients & families {#patients}

This is a change in the CFB gene that is currently of uncertain significance — a definitive interpretation has not yet been established, submitted by 1 submitter, and is linked to atypical hemolytic-uremic syndrome.

*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.*

|  |  |
| --- | --- |
| Typical inheritance (of this condition) | Autosomal dominant, Autosomal recessive, Not applicable |
| Age of onset (of this condition) | All ages |
| Prevalence | 1-9 / 1 000 000 (United States) |
| Clinical trials | 40 registered for this condition — see ClinicalTrials.gov |
| Diagnostic panels | CFB is a diagnostic-grade gene on 5 Genomics England panels |

**Commonly reported features of Atypical hemolytic uremic syndrome** (across patients with this condition; presentation varies — frequencies from Orphanet):

- Proteinuria — Very frequent (99-80%)
- Hematuria — Very frequent (99-80%)
- Abnormality of blood and blood-forming tissues — Very frequent (99-80%)
- Thrombocytopenia — Very frequent (99-80%)
- Acute kidney injury — Very frequent (99-80%)
- Microangiopathic hemolytic anemia — Very frequent (99-80%)
- Abnormality of metabolism/homeostasis — Very frequent (99-80%)
- Abnormal lactate dehydrogenase activity — Very frequent (99-80%)

**Support & next steps:** [Condition overview & support (NIH GARD)](https://rarediseases.info.nih.gov/diseases/0008702/index) · [Find a genetic counselor (NSGC)](https://findageneticcounselor.nsgc.org/).

## Identity {#identity}

| Field | Value |
| --- | --- |
| Gene | [CFB](https://sugi.bio/atlas/gene/CFB/) |
| Protein change (HGVS p.) | p.Ser687fs |
| Coding change (HGVS c.) | c.2058_2061del |
| MANE Select transcript | [NM_001710](https://www.ncbi.nlm.nih.gov/nuccore/NM_001710) |
| Variant type | Microsatellite |
| Location | chr6:31951438-31951441 (GRCh38) |
| ClinVar | [VCV4280386](https://www.ncbi.nlm.nih.gov/clinvar/variation/4280386/) |

**All HGVS expressions:** `LRG_136:g.10495GAGT[1]`, `LRG_136t1:c.2054_2057GAGT[1]`, `NC_000006.11:g.31919215GAGT[1]`, `NC_000006.12:g.31951438GAGT[1]`, `NG_008191.1:g.10495GAGT[1]`, `NM_001710.6:c.2058_2061del`

## Computational & population evidence {#evidence}

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

- **Missense predictors (AlphaMissense/REVEL/SaProt) do not apply** to this variant type — they score amino-acid substitutions only. For non-missense variants the computational signal comes from conservation (below), not from a missing predictor score.
- Conservation: phyloP 11.88, GERP 1.72, phastCons 1 — highly conserved position (PP3-type support)
- Molecular consequence: **frameshift** — a predicted loss-of-function variant. Gene population constraint: LOEUF 0.719, pLI 1.4693e-10. For a truncating variant the loss-of-function impact is position-dependent — C-terminal / last-exon truncations may escape nonsense-mediated decay. *Descriptive; not an applied PVS1 code.*
- SpliceAI: **not assessed** — the release is built from a substitutions-only source, so it holds no microsatellite variants. That is a property of the dataset, not of the variant, and is not evidence against a splicing effect.
- Population frequency (gnomAD v4.1): grpmax **0.000254%** (nfe) · FAF95 6.8e-05% · FAF99 1.9e-05% · 3/1,180,026 in the highest group · 3/1,461,894 alleles overall — very rare (popmax 0.000254%, nfe).

*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}

**CFB** population constraint: LOEUF 0.719, pLI 1.4693e-10, missense-Z 2.7519. *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** — Limited (AD)
- **atypical hemolytic-uremic syndrome with B factor anomaly** — Moderate (AD)

## Protein context {#protein}

Residue **687** lies in a β-strand; the peptidase s1 domain.

AlphaFold model confidence (whole protein): pLDDT 86.54, 65% of residues very-high.

**28 experimental structure(s)** (PDB): [11MG](https://www.rcsb.org/structure/11MG), [11MH](https://www.rcsb.org/structure/11MH), [1DLE](https://www.rcsb.org/structure/1DLE), [1Q0P](https://www.rcsb.org/structure/1Q0P), [1RRK](https://www.rcsb.org/structure/1RRK), [1RS0](https://www.rcsb.org/structure/1RS0).

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

*Describes the biological roles of CFB (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.*


### Pathways affected {#pathways}

CFB participates in **3 Reactome pathways** (⚕ = disease pathway):

| Pathway (Reactome) | Evidence |
| --- | --- |
| [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 |
| [Regulation of Complement cascade](https://reactome.org/content/detail/R-HSA-977606) | curated |

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

**Biological process:** complement activation, alternative pathway.

## Clinical significance {#significance}

**Uncertain significance** — review status Single submitter *(criteria provided, single submitter)*, last evaluated 2025-09-26.

**Submitter consensus:** unanimous (1/1 Uncertain significance).

### Submitter classifications {#submitters}

| Submitter | Classification | Review | Method | Date |
| --- | --- | --- | --- | --- |
| Genomenon, Inc, Genomenon, Inc | Uncertain significance | criteria provided, single submitter | curation | 2025-09-26 |

## Associated conditions {#conditions}

[atypical hemolytic-uremic syndrome](https://sugi.bio/atlas/disease/atypical-hemolytic-uremic-syndrome/).

**Reported phenotype names (ClinVar):** Atypical hemolytic-uremic syndrome.

## Similar variants {#similar}

Related CFB variant pages (same residue, condition, or type): [CFB p.Arg138Gln](/variant/cfb-p-arg138gln), [CFB p.Arg138Trp](/variant/cfb-p-arg138trp), [CFB p.Arg203Gln](/variant/cfb-p-arg203gln), [CFB p.Arg379Cys](/variant/cfb-p-arg379cys), [CFB p.Gln256Ter](/variant/cfb-p-gln256ter), [CFB p.Glu601Lys](/variant/cfb-p-glu601lys), [CFB p.Ser284Asn](/variant/cfb-p-ser284asn), [CFB c.1036+111A>G](/variant/cfb-c-1036-plus-111a-g).

### 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 4280386). 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.*