rs397517073

chr15-34791254-T-A

Variant summary

Our verdict is Uncertain significance. Variant got 5 ACMG points: 5P and 0B. PM2 PP2 PP3_Moderate

The NM_005159.5(ACTC1):c.850A>T(p.Ile284Phe) variant causes a missense change. The variant allele was found at a frequency of 0.000000684 in 1,461,772 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 (★★). Synonymous variant affecting the same amino acid position (i.e. I284I) has been classified as Likely benign.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: ACTC1 NM_005159.5 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:3
• Conservation: PhyloP100: 5.08

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 Uncertain_significance. Variant got 5 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP2: Missense variant where missense usually causes diseases, ACTC1
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.937

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
ACTC1	NM_005159.5	c.850A>T	p.Ile284Phe	missense_variant	6/7	ENST00000290378.6
GJD2-DT	NR_120329.1	n.299+13823T>A		intron_variant, non_coding_transcript_variant

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
ACTC1	ENST00000290378.6	c.850A>T	p.Ile284Phe	missense_variant	6/7	1	NM_005159.5	P1
GJD2-DT	ENST00000671663.1	n.95-19242T>A		intron_variant, non_coding_transcript_variant

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461772 Hom.: 0 Cov.: 31 AF XY: 0.00000138 AC XY: 1 AN XY: 727188

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: 8.99e-7

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:3

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not specified Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine

May 15, 2014

The Ile284Phe variant in ACTC1 has not been previously reported in individuals w ith cardiomyopathy and was absent from large population studies. This variant ha s been identified by our laboratory in 1 African American infant with HCM (who c arried a variant of uncertain significance in another gene) and was found to seg regate with disease in an affected sibling (who did not carry the other variant) . Computational prediction tools and conservation analyses do not provide strong support for or against an impact to the protein. In summary, the clinical signi ficance of the Ile284Phe variant is uncertain. -

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

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

Oct 27, 2022

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. 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. ClinVar contains an entry for this variant (Variation ID: 45191). This missense change has been observed in individual(s) with hypertrophic cardiomyopathy (PMID: 27532257). This variant is not present in population databases (gnomAD no frequency). This sequence change replaces isoleucine, which is neutral and non-polar, with phenylalanine, which is neutral and non-polar, at codon 284 of the ACTC1 protein (p.Ile284Phe). -

Hypertrophic cardiomyopathy Uncertain:1

Uncertain significance, criteria provided, single submitter

research

Agnes Ginges Centre for Molecular Cardiology, Centenary Institute

Dec 13, 2017

ACTC1 Ile284Phe has not been previously identified in literature but has been reported by another laboratory in an affected African American infant with HCM, and their affected brother (LMM; ClinVar SCV000062013.3). We identified this variant in a HCM proband of North-West European ancestry with a family history of HCM, however segregation was not possible. This variant is rare and is absent in the 1000 genomes project (http://www.1000genomes.org/), as well as the Exome Aggregation Consortium dataset (http://exac.broadinstitute.org/) and the Genome Aggregation Database (http://gnomad.broadinstitute.org/). Computational tools SIFT, MutationTaster, and PolyPhen-2 predict this variant to have a deleterious effect. In summary, based on the limited literature and rarity in general populations we classify ACTC1 Ile284Phe as a variant of "uncertain significance". -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.98
CardioboostCm	Pathogenic	1.0
BayesDel_addAF	Pathogenic	0.53	D
BayesDel_noAF	Pathogenic	0.52
Cadd	Pathogenic	28
Dann	Uncertain	0.98
DEOGEN2	Pathogenic	0.98	D
Eigen	Pathogenic	0.69
Eigen_PC	Pathogenic	0.67
FATHMM_MKL	Uncertain	0.97	D
LIST_S2	Uncertain	0.96	D
M_CAP	Pathogenic	0.40	D
MetaRNN	Pathogenic	0.94	D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Pathogenic	4.6	H
MutationTaster	Benign	1.0	D
PrimateAI	Pathogenic	0.89	D
PROVEAN	Uncertain	-3.0	D
REVEL	Pathogenic	0.92
Sift4G	Pathogenic	0.0	D
Polyphen		0.50	P
Vest4		0.87
MutPred		0.77		Loss of ubiquitination at K286 (P = 0.1139);
MVP		0.99
MPC		3.8
ClinPred		1.0	D
GERP RS		5.5
Varity_R		0.96
gMVP		0.99

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.030		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: rs397517073; hg19: chr15-35083455;