# NM_000390.4(CHM):c.115dup (p.Ser39fs)

https://sugi.bio/variant/chm-p-ser39fs

## Summary

**CHM p.Ser39fs (c.115dup)** is classified **Pathogenic** in CHM (ClinVar, Single submitter, 1 submitter; last evaluated 2024-11-12).

**At a glance:** Pathogenic · review: Single submitter · 1 submitter

## For patients & families {#patients}

This is a change in the CHM gene that is reported as disease-causing, but on limited review, submitted by 1 submitter.

*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 | [CHM](https://sugi.bio/atlas/gene/CHM/) |
| Protein change (HGVS p.) | p.Ser39fs |
| Coding change (HGVS c.) | c.115dup |
| MANE Select transcript | [NM_000390](https://www.ncbi.nlm.nih.gov/nuccore/NM_000390) |
| Variant type | Duplication |
| Location | chrX:86027491-86027492 (GRCh38) |
| ClinVar | [VCV3725069](https://www.ncbi.nlm.nih.gov/clinvar/variation/3725069/) |

**All HGVS expressions:** `LRG_699:g.25071dup`, `LRG_699t1:c.114dup`, `LRG_699t2:c.114dup`, `NC_000023.10:g.85282497dup`, `NC_000023.11:g.86027493dup`, `NG_009874.2:g.25071dup`, `NM_000390.4:c.115dup`, `NM_001145414.4:c.115dup`, `NM_001320959.1:c.-330dup`, `NM_001362517.1:c.-330dup`, `NM_001362518.2:c.-326dup`, `NM_001362519.1:c.-326dup`

## 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 8.152, GERP 2.1, phastCons 1 — highly conserved position (PP3-type support)
- Molecular consequence: **frameshift** — a predicted loss-of-function variant. ClinGen curates **sufficient evidence for haploinsufficiency** in this gene, supporting a loss-of-function disease mechanism. *Descriptive; not an applied PVS1 code.*
- Nonsense-mediated decay: the premature termination codon is **in exon 2 of 15**, so the transcript is predicted to undergo NMD.
- SpliceAI: **not assessed** — the release is built from a substitutions-only source, so it holds no duplication variants. That is a property of the dataset, not of the variant, and is not evidence against a splicing effect.

*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}

**CHM** population constraint: ClinGen dosage — haploinsufficiency 3, triplosensitivity 0 (0–3 scale). *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):

- **choroideremia** — Definitive (XL)

## Protein context {#protein}


AlphaFold model confidence (whole protein): pLDDT 81.05, 66% of residues very-high.

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

*Describes the biological roles of CHM (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:** CHM's established molecular role includes small GTPase binding.


### Pathways affected {#pathways}

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

| Pathway (Reactome) | Evidence |
| --- | --- |
| [RAB GEFs exchange GTP for GDP on RABs](https://reactome.org/content/detail/R-HSA-8876198) | curated |
| [RAB geranylgeranylation](https://reactome.org/content/detail/R-HSA-8873719) | curated |
| [TP53 regulates transcription of several additional cell death genes whose specific roles in p53-dependent apoptosis remain uncertain](https://reactome.org/content/detail/R-HSA-6803205) | curated |

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

**Molecular function:** small GTPase binding.

**Biological process:** protein targeting to membrane, protein geranylgeranylation.

## Clinical significance {#significance}

**Pathogenic** — review status Single submitter *(criteria provided, single submitter)*, last evaluated 2024-11-12.

**Submitter consensus:** unanimous (1/1 Pathogenic).

### Submitter classifications {#submitters}

| Submitter | Classification | Review | Method | Date |
| --- | --- | --- | --- | --- |
| Labcorp Genetics (formerly Invitae), Labcorp | Pathogenic | criteria provided, single submitter | clinical testing | 2024-11-12 |

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

## Similar variants {#similar}

Related CHM variant pages (same residue, condition, or type): [CHM p.Ser39Leu](/variant/chm-p-ser39leu), [CHM p.Asn283Ter](/variant/chm-p-asn283ter), [CHM p.Asp353fs](/variant/chm-p-asp353fs), [CHM p.Glu480fs](/variant/chm-p-glu480fs), [CHM c.117-27_117-26dup](/variant/chm-c-117-minus-27-117-minus-26dup), [CHM c.117-27dup](/variant/chm-c-117-minus-27dup), [CHM p.Asn644_Leu645insGlnSerThrAsn](/variant/chm-p-asn644-leu645insglnserthrasn), [CHM c.1609+2dup](/variant/chm-c-1609-plus-2dup).

### 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 3725069). 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.*