# NM_000124.4(ERCC6):c.229C>T (p.Arg77Ter)

https://sugi.bio/variant/ercc6-p-arg77ter

## Summary

**ERCC6 p.Arg77Ter (c.229C>T)** is classified **Pathogenic** in ERCC6 (ClinVar, Multiple submitters, 5 submitters; last evaluated 2023-07-16). Very rare (popmax 0.00223%, eas); Associated with ERCC6-related disorder.

**At a glance:** Pathogenic · review: Multiple submitters · rsID rs121917903 · 5 submitters · 4 linked conditions · very rare (popmax 0.00223%, eas)

## For patients & families {#patients}

This is a change in the ERCC6 gene that is considered disease-causing, submitted by 5 submitters, and is linked to ERCC6-related disorder.

*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 | [ERCC6](https://sugi.bio/atlas/gene/ERCC6/) |
| Protein change (HGVS p.) | p.Arg77Ter |
| Coding change (HGVS c.) | c.229C>T |
| MANE Select transcript | [NM_000124](https://www.ncbi.nlm.nih.gov/nuccore/NM_000124) |
| dbSNP | [rs121917903](https://www.ncbi.nlm.nih.gov/snp/rs121917903/) |
| Variant type | single nucleotide variant |
| Location | chr10:49532736-49532736 (GRCh38) |
| ClinVar | [VCV1708](https://www.ncbi.nlm.nih.gov/clinvar/variation/1708/) |

**All HGVS expressions:** `LRG_465:g.11366C>T`, `LRG_465t1:c.229C>T`, `NC_000010.10:g.50740782G>A`, `NC_000010.11:g.49532736G>A`, `NG_009442.1:g.11366C>T`, `NM_000124.3:c.229C>T`, `NM_000124.4:c.229C>T`, `NM_001277058.2:c.229C>T`, `NM_001277059.2:c.229C>T`, `NM_001346440.2:c.229C>T`

## Computational & population evidence {#evidence}

**Concordance:** 1 independent predictor **concordant** with the ClinVar classification.

- **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 2.649, GERP 0.862, phastCons 1 — highly conserved position (PP3-type support)
- Molecular consequence: **nonsense (stop-gain)** — a predicted loss-of-function variant. Gene population constraint: LOEUF 0.803, pLI 1.2087e-23. *Descriptive; not an applied PVS1 code.*
- Nonsense-mediated decay: the premature termination codon is **in exon 2 of 21**, so the transcript is predicted to undergo NMD.
- CADD: **PHRED 35.0**. 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.*
- 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 **0.00223%** (eas) · FAF95 0.0005% · FAF99 0.000366% · 1/44,890 in the highest group · 17/1,614,084 alleles overall — very rare (popmax 0.00223%, eas).

| Ancestry group | Allele frequency | 1 in |
| --- | --- | --- |
| Finnish (not grpmax-eligible) | 0.00312% | 32,019 |
| East Asian (grpmax) | 0.00223% | 44,890 |
| South Asian | 0.0022% | 45,548 |
| African / African-American | 0.00134% | 74,902 |
| European (non-Finnish) | 0.000932% | 107,278 |

Finnish shows a higher raw frequency than the grpmax group. gnomAD excludes bottlenecked groups — Finnish, Ashkenazi Jewish, Amish and "Remaining individuals" — from grpmax, because founder effects make their frequencies unrepresentative for filtering. The table is sorted by frequency, so an excluded group can sit above the grpmax row.

*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}

**ERCC6** population constraint: LOEUF 0.803, pLI 1.2087e-23, missense-Z 1.7245. *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):

- **Cockayne spectrum with or without cerebrooculofacioskeletal syndrome** — Definitive (AR)

## Protein context {#protein}

Residue **77** lies in the 'n-terminal domain; essential for its chromatin remodeling activity' region.

AlphaFold model confidence (whole protein): pLDDT 70.12, 32% of residues very-high.

**12 experimental structure(s)** (PDB): [4CVO](https://www.rcsb.org/structure/4CVO), [7OO3](https://www.rcsb.org/structure/7OO3), [7OOB](https://www.rcsb.org/structure/7OOB), [7OOP](https://www.rcsb.org/structure/7OOP), [7OPC](https://www.rcsb.org/structure/7OPC), [7OPD](https://www.rcsb.org/structure/7OPD).

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

*Describes the biological roles of ERCC6 (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:** ERCC6's established molecular role includes sequence-specific DNA binding. p.Arg77Ter falls in the n-terminal domain; essential for its chromatin remodeling activity region.


### Pathways affected {#pathways}

ERCC6 participates in **7 Reactome pathways** (⚕ = disease pathway):

| Pathway (Reactome) | Evidence |
| --- | --- |
| [B-WICH complex positively regulates rRNA expression](https://reactome.org/content/detail/R-HSA-5250924) | curated |
| [Dual incision in TC-NER](https://reactome.org/content/detail/R-HSA-6782135) | curated |
| [Formation of TC-NER Pre-Incision Complex](https://reactome.org/content/detail/R-HSA-6781823) | curated |
| [Gap-filling DNA repair synthesis and ligation in TC-NER](https://reactome.org/content/detail/R-HSA-6782210) | curated |
| [RNA Polymerase I Transcription Initiation](https://reactome.org/content/detail/R-HSA-73762) | curated |
| [Transcription-Coupled Nucleotide Excision Repair (TC-NER)](https://reactome.org/content/detail/R-HSA-6781827) | curated |
| [ERCC6 (CSB) and EHMT2 (G9a) positively regulate rRNA expression](https://reactome.org/content/detail/R-HSA-427389) | electronic |

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

**Molecular function:** sequence-specific DNA binding, DNA binding, chromatin binding, ATP binding, ATP-dependent activity, acting on DNA, protein tyrosine kinase activator activity.

**Biological process:** positive regulation of defense response to virus by host, positive regulation of gene expression, positive regulation of peptidyl-serine phosphorylation of STAT protein, positive regulation of DNA repair, single strand break repair, DNA damage checkpoint signaling.

## Clinical significance {#significance}

**Pathogenic** — review status Multiple submitters *(criteria provided, multiple submitters, no conflicts)*, last evaluated 2023-07-16.

**Submitter consensus:** unanimous (5/5 Pathogenic).

**Submission history:** 5 submissions (2012–2023); classifications have been stable.

### Submitter classifications {#submitters}

| Submitter | Classification | Review | Method | Date |
| --- | --- | --- | --- | --- |
| Genetic Services Laboratory, University of Chicago | Pathogenic | criteria provided, single submitter | clinical testing | 2015-10-29 |
| Women's Health and Genetics/Laboratory Corporation of America, LabCorp | Pathogenic | criteria provided, single submitter | clinical testing | 2023-04-15 |
| OMIM | Pathogenic | no assertion criteria provided | literature only | 2012-05-01 |
| Labcorp Genetics (formerly Invitae), Labcorp | Pathogenic | criteria provided, single submitter | clinical testing | 2023-07-16 |
| Blueprint Genetics | Pathogenic | criteria provided, single submitter | clinical testing | 2019-12-12 |

## Associated conditions {#conditions}

[ERCC6-related disorder](https://sugi.bio/atlas/disease/ercc6-related-disorder/), [UV-sensitive syndrome 1](https://sugi.bio/atlas/disease/uv-sensitive-syndrome-1/), [Cockayne syndrome](https://sugi.bio/atlas/disease/cockayne-syndrome/), [Cockayne syndrome type 2](https://sugi.bio/atlas/disease/cockayne-syndrome-type-2/).

**Reported phenotype names (ClinVar):** ERCC6-related disorder, UV-sensitive syndrome 1, Cockayne syndrome type 2, not provided, Cockayne syndrome, ERCC6-related disorders, ERCC6-related condition, none provided, COCKAYNE SYNDROME B, Cockayne Syndrome, Type II.

## Similar variants {#similar}

Related ERCC6 variant pages (same residue, condition, or type): [ERCC6 p.Arg77=](/variant/ercc6-p-arg77), [ERCC6 c.1397+1G>C](/variant/ercc6-c-1397-plus-1g-c), [ERCC6 c.1526+1G>T](/variant/ercc6-c-1526-plus-1g-t), [ERCC6 c.2169+1G>A](/variant/ercc6-c-2169-plus-1g-a), [ERCC6 c.2170-1G>A](/variant/ercc6-c-2170-minus-1g-a), [ERCC6 c.2286+1G>A](/variant/ercc6-c-2286-plus-1g-a), [ERCC6 c.2287-2A>G](/variant/ercc6-c-2287-minus-2a-g), [ERCC6 c.2599-26A>G](/variant/ercc6-c-2599-minus-26a-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 1708). 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.*