15-34793521-C-T

Variant names:

• chr15-34793521-C-T
• rs1555418912
• NM_005159.5:c.178G>A

Variant summary

Our verdict is Likely pathogenic. The variant received 8 ACMG points: 8P and 0B. PM1 PM2 PP3_Strong

The NM_005159.5(ACTC1):​c.178G>A​(p.Ala60Thr) variant causes a missense change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. 13/23 in silico tools predict a damaging outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. A60S) has been classified as Uncertain significance.

• Frequency: Genomes: not found (cov: 32)
• Consequence: ACTC1 NM_005159.5 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:3
• Conservation: PhyloP100: 7.91
• Publications: 0 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: Likely_pathogenic. The variant received 8 ACMG points.

• PM1: In a hotspot region, there are 2 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 7 uncertain in NM_005159.5
• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.962

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
ACTC1	NM_005159.5	c.178G>A	p.Ala60Thr	missense_variant	Exon 3 of 7	ENST00000290378.6	NP_005150.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
ACTC1	ENST00000290378.6	c.178G>A	p.Ala60Thr	missense_variant	Exon 3 of 7	1	NM_005159.5	ENSP00000290378.4

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:3

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Cardiomyopathy Uncertain:1

Oct 30, 2017

CHEO Genetics Diagnostic Laboratory, Children's Hospital of Eastern Ontario

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

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

Dec 14, 2023

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces alanine, which is neutral and non-polar, with threonine, which is neutral and polar, at codon 60 of the ACTC1 protein (p.Ala60Thr). This variant is not present in population databases (gnomAD no frequency). This variant has not been reported in the literature in individuals affected with ACTC1-related conditions. ClinVar contains an entry for this variant (Variation ID: 538805). Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) has been performed at Invitae for this missense variant, however the output from this modeling did not meet the statistical confidence thresholds required to predict the impact of this variant on ACTC1 protein function. 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. -

Hypertrophic cardiomyopathy Uncertain:1

Aug 08, 2023

All of Us Research Program, National Institutes of Health

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This missense variant replaces alanine with threonine at codon 60 of the ACTC1 protein. Computational prediction suggests that this variant may have deleterious impact on protein structure and function (internally defined REVEL score threshold >= 0.7, PMID: 27666373). To our knowledge, functional studies have not been reported for this variant. This variant has not been reported in individuals affected with ACTC1-related disorders in the literature. This variant has not been identified in the general population by the Genome Aggregation Database (gnomAD). The available evidence is insufficient to determine the role of this variant in disease conclusively. Therefore, this variant is classified as a Variant of Uncertain Significance. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.99
CardioboostCm	Pathogenic	0.99
BayesDel_addAF	Pathogenic	0.34	D
BayesDel_noAF	Pathogenic	0.26
CADD	Pathogenic	31
DANN	Uncertain	0.98
DEOGEN2	Pathogenic	0.94	D
Eigen	Pathogenic	0.99
Eigen_PC	Pathogenic	0.92
FATHMM_MKL	Uncertain	0.94	D
LIST_S2	Uncertain	0.93	D
M_CAP	Pathogenic	0.66	D
MetaRNN	Pathogenic	0.96	D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Pathogenic	4.3	H
PhyloP100		7.9
PrimateAI	Pathogenic	0.86	D
PROVEAN	Benign	-2.1	N
REVEL	Pathogenic	0.88
Sift4G	Uncertain	0.0090	D
Polyphen		0.83	P
Vest4		0.76
MutPred		0.85		Gain of phosphorylation at A60 (P = 0.0511);
MVP		0.98
MPC		2.7
ClinPred		1.0	D
GERP RS		5.5
Varity_R		0.79
gMVP		0.97
Mutation Taster		=55/45	polymorphism

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: rs1555418912; hg19: chr15-35085722;