ACTA2 R256C (c.766C>T, rs886038852)

Dante Labs

Sequence your genome

Variant

ACTA2 R256C

NM_001613.4(ACTA2):c.766C>T (p.Arg256Cys)

Also known as

p.Arg256Cys
p.R256C
rs886038852

ClinVar classification: Likely pathogenic
Review status: 2 stars out of 4criteria provided, multiple submitters, no conflicts
Last evaluated: 23 December 2025

Data current to ClinVar release 2026-10-12 · Dante Labs data release 2026.10.19-9814e911Facts last changed 19 October 2026

This page as data

Add .json to the page's address, or ask for application/json, to read it as JSON.

library(jsonlite)

url <- "https://dantelabs.com/genes/acta2/variants/r256c.json"
page <- fromJSON(url)
page$variant$name

Open the JSON

Summary

R256C is a missense variant in ACTA2: it changes a single amino acid in the protein the gene encodes. ClinVar classifies it as likely pathogenic for aortic aneurysm, familial thoracic 6 (criteria provided, multiple submitters, no conflicts). ClinVar also lists it under 1 more condition.

ClinVar classifications

Condition	Classification	Review status	Submissions	Last evaluated
aortic aneurysm, familial thoracic 6ClinVar VCV000263578 (opens in a new tab)	Likely pathogenic	2 stars out of 4criteria provided, multiple submitters, no conflicts	3 submissions	23 December 2025
Familial Thoracic Aortic Aneurysm and DissectionClinVar VCV000263578 (opens in a new tab)	Likely pathogenic	2 stars out of 4criteria provided, multiple submitters, no conflicts	2 submissions	30 October 2025

Classifications as ClinVar records them in release 2026-10-12. ClinVar updates them as evidence is reviewed.

ACMG/AMP criteria

The ACMG/AMP criteria R256C meets, from its predicted effect in ACTA2, gnomAD and ClinVar.

Criterion	Strength	Points	Rests on
PM5A different pathogenic change at the same amino acid	Moderate	+2	p.Arg256Ser at the same amino acid, ClinVar: Likely pathogenic (criteria provided, single submitter)
PP5A reputable source reports it as pathogenic	Supporting	Not counted	ClinVar: Likely pathogenic (criteria provided, multiple submitters, no conflicts)

On these criteria alone: +2 points, uncertain significance.

Assessed automatically, without functional, computational or family evidence. Not a clinical classification.

Population frequency

How often R256C is seen among the people whose exomes and genomes gnomAD 4.1 brings together.

Dataset	Allele frequency	Allele count	Homozygotes	Commonest in
gnomAD exomes	0.00021%1 in 487,243	3 of 1,461,728	0	European (non-Finnish): 0.00027%
gnomAD genomes	Not seen	0 of 0	0

Figures from gnomAD 4.1, as gnomAD publishes them. Groups are genetic ancestry groups as gnomAD infers them. They describe the variant in gnomAD's populations, not anyone's result.

R256C in the gnomAD browser (opens in a new tab)

Where it lies in ACTA2

R256C lies in exon 7 of the 9 in ACTA2's MANE Select transcript, NM_001613.4.

ACTA2 variants in exon 7 →ACTA2's gene diagram →

Molecular details

Gene	ACTA2
Transcript	NM_001613.4MANE Select
Coding DNA change (HGVS c.)	c.766C>T
Protein change (HGVS p.)	p.Arg256Cysp.R256C
Predicted consequence	Missensemissense_variant (opens in a new tab)
Predicted impact	Moderate
Position (GRCh38)	chr10:88939549 G>A
Position (GRCh37)	chr10:90699306 G>A
dbSNP ID	rs886038852 (opens in a new tab)
ClinVar Variation ID	VCV000263578 (opens in a new tab)
ClinVar Allele ID	258667
ClinGen Allele Registry ID	CA10587710 (opens in a new tab)
ClinVar name	NM_001613.4(ACTA2):c.766C>T (p.Arg256Cys)

ACTA2 R256C in other databases

Reports that look at this variant (1)

These Genome Test condition reports include R256C among the variants they look at.

Report	Conditions	Inheritance
Aortic Aneurysm	Familial Thoracic Aortic Aneurysm and Dissection	Autosomal dominant
Aortic Aneurysm	Multisystemic Smooth Muscle Dysfunction Syndrome	Autosomal dominant

All ACTA2 variants

Limitations

This page describes publicly available information about a genetic variant. It is not a diagnosis, and it says nothing about whether you or anyone else carries this variant.

Classifications come from ClinVar and change as new evidence is reviewed. A classification here may differ from the one in ClinVar today, or from the one a laboratory reports.

Whole genome sequencing with short reads can miss or miscall some variants, particularly in repeated or highly similar stretches of DNA and in large insertions, deletions or rearrangements.

If you have questions about a variant in your own results or in your family, talk to a genetic counsellor or your doctor.

Sources & credits

Classifications from ClinVar (release 2026-10-12), National Center for Biotechnology Information.
Condition terms from the Mondo Disease Ontology (release 2026-10-06), used under CC BY 4.0.
Gene symbols and names from the HUGO Gene Nomenclature Committee (release 2026-10-16).
Allele identifiers from the ClinGen Allele Registry (release 2026-10-19-c4908f54).
Reference SNP identifiers from dbSNP (release b157), National Center for Biotechnology Information.
Gene–disease links from the Gene Curation Coalition, GenCC (release 2026-10-19).
Difficult regions from the Genome in a Bottle Consortium (release v3.6).
Transcripts from MANE (release v1.5), NCBI and EMBL-EBI.
Predicted consequences from mehari (release 0.11.0), with transcript models from cdot.
Built from Dante Labs data release 2026.10.19-9814e911 of 19 October 2026.

Cite this page

APA

Dante Labs. (19 October 2026). ACTA2 R256C (c.766C>T, rs886038852) (Version 2026.10.19-9814e911). Retrieved 20 October 2026, from https://dantelabs.com/genes/acta2/variants/r256c

Vancouver

Dante Labs. ACTA2 R256C (c.766C>T, rs886038852) [Internet]. Version 2026.10.19-9814e911. 19 October 2026 [cited 20 October 2026]. Available from: https://dantelabs.com/genes/acta2/variants/r256c

Download citationRIS BibTeX CSL-JSON

Read your whole genome

From $449Free shipping · Results in 6–8 weeks

Explore the Genome Test