15-34793327-G-C

Position:

• chr15-34793327-G-C

Variant summary

Our verdict is Likely pathogenic. Variant got 9 ACMG points: 9P and 0B. PM1 PM2 PP2 PP3_Strong

The NM_005159.5(ACTC1):​c.372C>G​(p.Ile124Met) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000137 in 1,461,886 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000014 (0 hom.)
• Consequence: ACTC1 NM_005159.5 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:4
• Conservation: PhyloP100: 3.31

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

Verdict is Likely_pathogenic. Variant got 9 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, 9 uncertain in NM_005159.5
• PM2: Very rare variant in population databases, with high coverage
• PP2: Missense variant in gene, where missense usually causes diseases (based on misZ statistic), ACTC1. . Gene score misZ 4.5244 (greater than the threshold 3.09). Trascript score misZ 6.3156 (greater than threshold 3.09). GenCC has associacion of gene with dilated cardiomyopathy, hypertrophic cardiomyopathy, atrial septal defect 5, arrhythmogenic right ventricular cardiomyopathy, familial isolated dilated cardiomyopathy, dilated cardiomyopathy 1R, hypertrophic cardiomyopathy 11.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.946

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
ACTC1	NM_005159.5	c.372C>G	p.Ile124Met	missense_variant	3/7	ENST00000290378.6
GJD2-DT	NR_120329.1	n.299+15896G>C		intron_variant, non_coding_transcript_variant

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
ACTC1	ENST00000290378.6	c.372C>G	p.Ile124Met	missense_variant	3/7	1	NM_005159.5	P1
GJD2-DT	ENST00000671663.1	n.95-17169G>C		intron_variant, non_coding_transcript_variant

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 0.00000137 AC: 2 AN: 1461886 Hom.: 0 Cov.: 31 AF XY: 0.00000138 AC XY: 1 AN XY: 727244

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00000180

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:4

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Cardiomyopathy Uncertain:2

Uncertain significance, criteria provided, single submitter	clinical testing	Color Diagnostics, LLC DBA Color Health	Jul 06, 2021	This missense variant replaces isoleucine with methionine at codon 124 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 cardiovascular 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. -
Uncertain significance, criteria provided, single submitter	clinical testing	CHEO Genetics Diagnostic Laboratory, Children's Hospital of Eastern Ontario	Nov 21, 2019	- -

not specified Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine

Jan 22, 2013

The Ile124Met variant in ACTC has not been reported in the literature nor previo usly identified by our laboratory. This variant has also not been identified in large and broad European American and African American populations by the NHLBI Exome Sequencing Project (http://evs.gs.washington.edu/EVS), though it may be co mmon in other populations. Computational analyses (biochemical amino acid proper ties, conservation, AlignGVGD, PolyPhen2, and SIFT) do not provide strong suppor t for or against an impact to the protein. Additional information is needed to f ully assess the clinical significance of this variant. -

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

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Oct 12, 2023

This sequence change replaces isoleucine, which is neutral and non-polar, with methionine, which is neutral and non-polar, at codon 124 of the ACTC1 protein (p.Ile124Met). 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: 45177). 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) performed at Invitae indicates that this missense variant is not expected to disrupt 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. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.57
CardioboostCm	Pathogenic	0.95
BayesDel_addAF	Pathogenic	0.40	D
BayesDel_noAF	Pathogenic	0.33
CADD	Pathogenic	27
DANN	Uncertain	0.99
DEOGEN2	Pathogenic	0.90	D
Eigen	Uncertain	0.59
Eigen_PC	Uncertain	0.61
FATHMM_MKL	Uncertain	0.89	D
LIST_S2	Uncertain	0.93	D
M_CAP	Pathogenic	0.36	D
MetaRNN	Pathogenic	0.95	D
MetaSVM	Pathogenic	1.0	D
MutationAssessor	Uncertain	2.6	M
MutationTaster	Benign	1.0	D
PrimateAI	Pathogenic	0.88	D
PROVEAN	Benign	-2.1	N
REVEL	Pathogenic	0.84
Sift4G	Uncertain	0.013	D
Polyphen		0.15	B
Vest4		0.85
MutPred		0.83		Gain of disorder (P = 0.0325);
MVP		0.99
MPC		2.8
ClinPred		0.95	D
GERP RS		5.6
Varity_R		0.84
gMVP		0.97

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.040		Details are displayed if max score is > 0.2

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

Publications

LitVar

Other links and lift over

dbSNP: rs397517061; hg19: chr15-35085528;