NM_005159.5:c.793C>G

Variant names:

• chr15-34792105-G-C
• rs727504323
• NM_005159.5:c.793C>G

Variant summary

Our verdict is Uncertain significance. The variant received 5 ACMG points: 5P and 0B. PM1 PM2 PP5

The NM_005159.5(ACTC1):​c.793C>G​(p.Gln265Glu) variant causes a missense change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. Q265H) has been classified as Uncertain significance.

• Frequency: Genomes: not found (cov: 32)
• Consequence: ACTC1 NM_005159.5 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:2 U:2
• Conservation: PhyloP100: 9.71
• Publications: 2 publications found

Genes affected

ACTC1 (HGNC:143): (actin alpha cardiac muscle 1) Actins are highly conserved proteins that are involved in various types of cell motility. Polymerization of globular actin (G-actin) leads to a structural filament (F-actin) in the form of a two-stranded helix. Each actin can bind to four others. The protein encoded by this gene belongs to the actin family which is comprised of three main groups of actin isoforms, alpha, beta, and gamma. The alpha actins are found in muscle tissues and are a major constituent of the contractile apparatus. Defects in this gene have been associated with idiopathic dilated cardiomyopathy (IDC) and familial hypertrophic cardiomyopathy (FHC). [provided by RefSeq, Jul 2008]

GJD2-DT (HGNC:55560): (GJD2 divergent transcript)

ACMG classification

Our verdict: Uncertain_significance. The variant received 5 ACMG points.

• PM1: In a hotspot region, there are 3 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 10 uncertain in NM_005159.5
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 15-34792105-G-C is Pathogenic according to our data. Variant chr15-34792105-G-C is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 177786.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_005159.5. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	ACTC1	NM_005159.5	MANE Select	c.793C>G	p.Gln265Glu	missense	Exon 5 of 7	NP_005150.1
	ACTC1	NM_001406482.1		c.793C>G	p.Gln265Glu	missense	Exon 4 of 6	NP_001393411.1
	ACTC1	NM_001406483.1		c.793C>G	p.Gln265Glu	missense	Exon 5 of 7	NP_001393412.1

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	ACTC1	ENST00000290378.6	TSL:1 MANE Select	c.793C>G	p.Gln265Glu	missense	Exon 5 of 7	ENSP00000290378.4
	ACTC1	ENST00000713613.1		c.904C>G	p.Gln302Glu	missense	Exon 6 of 8	ENSP00000518909.1
	ACTC1	ENST00000713610.1		c.793C>G	p.Gln265Glu	missense	Exon 5 of 7	ENSP00000518905.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 32

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:2 Uncertain:2

Revision: criteria provided, conflicting classifications

Submissions by phenotype

not provided Pathogenic:1

Feb 21, 2020

Mayo Clinic Laboratories, Mayo Clinic

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

PP1_Strong, PM2, PP2

Hypertrophic cardiomyopathy Pathogenic:1

Nov 21, 2018

Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The p.Gln265Glu variant in ACTC1 has been identified in 4 individuals with hyper trophic cardiomyopathy (HCM) and segregated with disease in 7 affected relatives (including 1 obligate carrier) from 3 families (LMM data, GeneDx pers. comm., A mbry pers. comm.). This variant has also been reported by other clinical laborat ories in ClinVar (Variation ID 177786) and was absent from large population stud ies. Computational prediction tools and conservation analysis do not provide str ong support for or against an impact to the protein. In summary, although additi onal studies are required to fully establish its clinical significance, this var iant meets criteria to be classified as likely pathogenic for autosomal dominant HCM. ACMG/AMP Criteria applied: PP1_Strong, PM2, PS4_Supporting.

Hypertrophic cardiomyopathy 11;C2748552:Atrial septal defect 5;C3150681:Dilated cardiomyopathy 1R Uncertain:1

Feb 18, 2022

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant is not present in population databases (gnomAD no frequency). In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. Algorithms developed to predict the effect of missense changes on protein structure and function (SIFT, PolyPhen-2, Align-GVGD) all suggest that this variant is likely to be tolerated. ClinVar contains an entry for this variant (Variation ID: 177786). This missense change has been observed in individual(s) with hypertrophic cardiomyopathy (PMID: 27532257). This sequence change replaces glutamine, which is neutral and polar, with glutamic acid, which is acidic and polar, at codon 265 of the ACTC1 protein (p.Gln265Glu).

Cardiovascular phenotype Uncertain:1

Sep 09, 2025

Ambry Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The p.Q265E variant (also known as c.793C>G), located in coding exon 4 of the ACTC1 gene, results from a C to G substitution at nucleotide position 793. The glutamine at codon 265 is replaced by glutamic acid, an amino acid with highly similar properties. This variant was reported in individual(s) with features consistent with hypertrophic cardiomyopathy (Alfares AA et al. Genet Med, 2015 Nov;17:880-8; Walsh R et al. Genet Med, 2017 Feb;19:192-203; McGurk KA et al. Am J Hum Genet, 2023 Sep;110:1482-1495; Ambry internal data). This amino acid position is highly conserved in available vertebrate species. In addition, this alteration is predicted to be deleterious by in silico analysis. Based on the available evidence, the clinical significance of this variant remains unclear.

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.57
CardioboostCm	Uncertain	0.76
BayesDel_addAF	Pathogenic	0.40	D
BayesDel_noAF	Pathogenic	0.34
CADD	Pathogenic	28
DANN	Benign	0.95
DEOGEN2	Pathogenic	0.86	D
Eigen	Uncertain	0.40
Eigen_PC	Uncertain	0.47
FATHMM_MKL	Pathogenic	1.0	D
LIST_S2	Uncertain	0.94	D
M_CAP	Pathogenic	0.58	D
MetaRNN	Uncertain	0.66	D
MetaSVM	Pathogenic	0.99	D
MutationAssessor	Pathogenic	3.1	M
PhyloP100		9.7
PrimateAI	Uncertain	0.79	T
PROVEAN	Benign	-1.9	N
REVEL	Pathogenic	0.88
Sift4G	Uncertain	0.020	D
Polyphen		0.038	B
Vest4		0.53
MutPred		0.66		Gain of relative solvent accessibility (P = 0.09)
MVP		0.98
MPC		1.7
ClinPred		0.96	D
GERP RS		4.5
Varity_R		0.92
gMVP		0.99
Mutation Taster		=22/78	disease causing (ClinVar)

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.0		Details are displayed if max score is > 0.2

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Other links and lift over

dbSNP: rs727504323; hg19: chr15-35084306;