chr15-63064120-G-A

Variant names:

• chr15-63064120-G-A
• rs149659674
• NM_001018005.2:c.829G>A

Variant summary

Our verdict is Likely benign. The variant received -5 ACMG points: 0P and 5B. BP4 BS2

The NM_001018005.2(TPM1):​c.829G>A​(p.Ala277Thr) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.0000167 in 1,613,872 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign 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. A277G) has been classified as Uncertain significance.

• Frequency:
  • Genomes: 𝑓 0.000085 (0 hom., cov: 33)
  • Exomes 𝑓: 0.0000096 (0 hom.)
• Consequence: TPM1 NM_001018005.2 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:7
• Conservation: PhyloP100: 10.0
• Publications: 4 publications found

Genes affected

TPM1 (HGNC:12010): (tropomyosin 1) This gene is a member of the tropomyosin family of highly conserved, widely distributed actin-binding proteins involved in the contractile system of striated and smooth muscles and the cytoskeleton of non-muscle cells. Tropomyosin is composed of two alpha-helical chains arranged as a coiled-coil. It is polymerized end to end along the two grooves of actin filaments and provides stability to the filaments. The encoded protein is one type of alpha helical chain that forms the predominant tropomyosin of striated muscle, where it also functions in association with the troponin complex to regulate the calcium-dependent interaction of actin and myosin during muscle contraction. In smooth muscle and non-muscle cells, alternatively spliced transcript variants encoding a range of isoforms have been described. Mutations in this gene are associated with type 3 familial hypertrophic cardiomyopathy and dilated cardiomyopathy 1Y. [provided by RefSeq, Jun 2022]

TPM1 Gene-Disease associations (from GenCC):

• hypertrophic cardiomyopathy

  Inheritance: AD Classification: DEFINITIVE Submitted by: ClinGen
• hypertrophic cardiomyopathy 3

  Inheritance: AD Classification: DEFINITIVE, STRONG Submitted by: Labcorp Genetics (formerly Invitae), PanelApp Australia, G2P
• dilated cardiomyopathy 1Y

  Inheritance: AD Classification: STRONG Submitted by: Labcorp Genetics (formerly Invitae)
• dilated cardiomyopathy

  Inheritance: AD Classification: MODERATE Submitted by: ClinGen
• familial isolated dilated cardiomyopathy

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• left ventricular noncompaction

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• arrhythmogenic right ventricular cardiomyopathy

  Inheritance: AD Classification: NO_KNOWN Submitted by: ClinGen

ACMG classification

Our verdict: Likely_benign. The variant received -5 ACMG points.

• BP4: Computational evidence support a benign effect (MetaRNN=0.27957192).
• BS2: High AC in GnomAd4 at 13 AD gene.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
TPM1	NM_001018005.2	c.829G>A	p.Ala277Thr	missense_variant	Exon 9 of 10	ENST00000403994.9	NP_001018005.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
TPM1	ENST00000403994.9	c.829G>A	p.Ala277Thr	missense_variant	Exon 9 of 10	1	NM_001018005.2	ENSP00000385107.4

Frequencies

GnomAD3 genomes AF: 0.0000854 AC: 13 AN: 152160 Hom.: 0 Cov.: 33

Gnomad AFR AF: 0.000290

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.0000655

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.00

Gnomad OTH AF: 0.00

GnomAD2 exomes AF: 0.0000199 AC: 5 AN: 251036 AF XY: 0.0000147

Gnomad AFR exome AF: 0.000123

Gnomad AMR exome AF: 0.0000868

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000958 AC: 14 AN: 1461712 Hom.: 0 Cov.: 31 AF XY: 0.00000275 AC XY: 2 AN XY: 727148

African (AFR) AF: 0.000209 AC: 7 AN: 33478

American (AMR) AF: 0.0000447 AC: 2 AN: 44706

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26132

East Asian (EAS) AF: 0.0000252 AC: 1 AN: 39700

South Asian (SAS) AF: 0.0000116 AC: 1 AN: 86194

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53386

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5768

European-Non Finnish (NFE) AF: 0.00000180 AC: 2 AN: 1111954

Other (OTH) AF: 0.0000166 AC: 1 AN: 60394

GnomAD4 genome AF: 0.0000854 AC: 13 AN: 152160 Hom.: 0 Cov.: 33 AF XY: 0.000121 AC XY: 9 AN XY: 74336

African (AFR) AF: 0.000290 AC: 12 AN: 41428

American (AMR) AF: 0.0000655 AC: 1 AN: 15274

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 3470

East Asian (EAS) AF: 0.00 AC: 0 AN: 5182

South Asian (SAS) AF: 0.00 AC: 0 AN: 4832

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10612

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 316

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 68040

Other (OTH) AF: 0.00 AC: 0 AN: 2094

Alfa AF: 0.0000987 Hom.: 0

Bravo AF: 0.000106

ESP6500AA AF: 0.000227 AC: 1

ESP6500EA AF: 0.00 AC: 0

ExAC AF: 0.0000330 AC: 4

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:7

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Hypertrophic cardiomyopathy Uncertain:2

Nov 20, 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 277 of the TPM1 protein. Computational prediction suggests that this variant may not impact protein structure and function (internally defined REVEL score threshold <= 0.5, PMID: 27666373). To our knowledge, functional studies have not been reported for this variant. This variant has been reported in individuals affected with hypertrophic cardiomyopathy (PMID: 27532257) and dilated cardiomyopathy (PMID: 32880476). This variant has been identified in 8/282436 chromosomes 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. -

Jan 23, 2025

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 277 of the TPM1 protein (p.Ala277Thr). This variant is present in population databases (rs149659674, gnomAD 0.02%). This missense change has been observed in individual(s) with dilated cardiomyopathy, hypertrophic cardiomyopathy (PMID: 32880476, 37652022). ClinVar contains an entry for this variant (Variation ID: 43442). An algorithm developed to predict the effect of missense changes on protein structure and function (PolyPhen-2) suggests that this variant is likely to be tolerated. 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. -

not specified Uncertain:1

Oct 31, 2012

Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Variant classified as Uncertain Significance - Favor Benign. The Ala277Thr varia nt in TPM1 has not been reported in the literature. This variant has been identi fied in 2 Black individuals with HCM tested by our laboratory (including this in dividual) and has been identified in 1/4406 African American chromosomes from a broad population by the NHLBI Exome Sequencing Project (http://evs.gs.washington .edu/EVS; dbSNP rs149659674). Alanine (Ala) at position 277 is not well conserve d in evolution with several species carrying the mutant amino acid (threonine). This suggests that this variant is tolerated but is insufficient to rule out a role in disease. Additional information is needed to fully assess the clinical s ignificance of the Ala277Thr variant. -

Cardiomyopathy Uncertain:1

Sep 28, 2023

Color Diagnostics, LLC DBA Color Health

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This missense variant replaces alanine with threonine at codon 277 of the TPM1 protein. Computational prediction suggests that this variant may not impact protein structure and function (internally defined REVEL score threshold <= 0.5, PMID: 27666373). To our knowledge, functional studies have not been reported for this variant. This variant has been reported in individuals affected with hypertrophic cardiomyopathy (PMID: 27532257) and dilated cardiomyopathy (PMID: 32880476). This variant has been identified in 8/282436 chromosomes 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. -

Hypertrophic cardiomyopathy 3;C2678476:Dilated cardiomyopathy 1Y Uncertain:1

Sep 03, 2021

Fulgent Genetics, Fulgent Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

not provided Uncertain:1

Jun 28, 2024

GeneDx

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

In silico analysis indicates that this missense variant does not alter protein structure/function; This variant is associated with the following publications: (PMID: 34699384, 34194005, 32880476) -

Cardiovascular phenotype Uncertain:1

Aug 26, 2023

Ambry Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The p.A277T variant (also known as c.829G>A), located in coding exon 9 of the TPM1 gene, results from a G to A substitution at nucleotide position 829. The alanine at codon 277 is replaced by threonine, an amino acid with similar properties. This variant has been reported in hypertrophic and dilated cardiomyopathy cohorts, but clinical details were limited (Alfares AA et al. Genet Med, 2015 Nov;17:880-8; Stroeks SLVM et al. Genet Med, 2021 Nov;23:2186-2193). This amino acid position is highly conserved in available vertebrate species. In addition, the in silico prediction for this alteration is inconclusive. Since supporting evidence is limited at this time, the clinical significance of this alteration remains unclear. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Uncertain	0.41
CardioboostCm	Benign	0.014
BayesDel_addAF	Pathogenic	0.17	D
BayesDel_noAF	Pathogenic	0.25
CADD	Uncertain	25
DANN	Benign	0.46
DEOGEN2	Uncertain	0.66	.;D;.;.;.;T
Eigen	Benign	-0.22
Eigen_PC	Benign	0.10
FATHMM_MKL	Pathogenic	0.97	D
LIST_S2	Uncertain	0.95	D;D;D;D;D;D
M_CAP	Uncertain	0.19	D
MetaRNN	Benign	0.28	T;T;T;T;T;T
MetaSVM	Uncertain	0.014	D
MutationAssessor	Benign	-0.92	N;N;N;.;.;.
PhyloP100		10
PROVEAN	Benign	1.0	N;N;.;.;.;N
REVEL	Uncertain	0.45
Sift	Benign	1.0	T;T;.;.;.;T
Sift4G	Benign	1.0	T;T;.;.;.;T
Polyphen		0.0, 0.0010	.;B;B;.;.;.
Vest4		0.77
MVP		0.98
ClinPred		0.15	T
GERP RS		5.8
Varity_R		0.37
Mutation Taster		=2/98	disease causing

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: rs149659674; hg19: chr15-63356319;