rs727503518

Variant names:

• chr15-63062230-G-A
• rs727503518
• NM_001018005.2:c.655G>A

Variant summary

Our verdict is Likely pathogenic. Variant got 9 ACMG points: 9P and 0B. PM1 PM2 PM5 PP2 PP3 PP5

The NM_001018005.2(TPM1):​c.655G>A​(p.Asp219Asn) 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. 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. D219E) has been classified as Likely pathogenic.

• Frequency: Genomes: not found (cov: 33)
• Consequence: TPM1 NM_001018005.2 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:1 U:2
• Conservation: PhyloP100: 9.88

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]

ACMG classification

Verdict is Likely_pathogenic. Variant got 9 ACMG points.

• PM1: In a chain Tropomyosin alpha-1 chain (size 283) in uniprot entity TPM1_HUMAN there are 61 pathogenic changes around while only 1 benign (98%) in NM_001018005.2
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr15-63062232-C-A is described in Lovd as [Likely_pathogenic].
• PP2: Missense variant in the TPM1 gene, where missense mutations are typically associated with disease (based on misZ statistic). The gene has 42 curated pathogenic missense variants (we use a threshold of 10). The gene has 25 curated benign missense variants. Gene score misZ: 2.8677 (below the threshold of 3.09). Trascript score misZ: 3.9402 (above the threshold of 3.09). GenCC associations: The gene is linked to dilated cardiomyopathy, left ventricular noncompaction, hypertrophic cardiomyopathy, hypertrophic cardiomyopathy 3, arrhythmogenic right ventricular cardiomyopathy, familial isolated dilated cardiomyopathy, dilated cardiomyopathy 1Y.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.836
• PP5: Variant 15-63062230-G-A is Pathogenic according to our data. Variant chr15-63062230-G-A is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 165571.We mark this variant Likely_pathogenic, oryginal submissions are: {Likely_pathogenic=1, Uncertain_significance=2}. Variant chr15-63062230-G-A is described in Lovd as [Likely_pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
TPM1	NM_001018005.2	c.655G>A	p.Asp219Asn	missense_variant	Exon 7 of 10	ENST00000403994.9	NP_001018005.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
TPM1	ENST00000403994.9	c.655G>A	p.Asp219Asn	missense_variant	Exon 7 of 10	1	NM_001018005.2	ENSP00000385107.4

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 33

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:1 Uncertain:2

Revision: criteria provided, conflicting classifications

Submissions by phenotype

Hypertrophic cardiomyopathy Pathogenic:1 Uncertain:1

Feb 14, 2013

Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

proposed classification - variant undergoing re-assessment, contact laboratory -

Apr 09, 2023

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

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. 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 disruptive. This sequence change replaces aspartic acid, which is acidic and polar, with asparagine, which is neutral and polar, at codon 219 of the TPM1 protein (p.Asp219Asn). This variant is not present in population databases (gnomAD no frequency). This missense change has been observed in individual(s) with hypertrophic cardiomyopathy (PMID: 25524337, 27532257). ClinVar contains an entry for this variant (Variation ID: 165571). -

Cardiovascular phenotype Uncertain:1

May 13, 2020

Ambry Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The p.D219N variant (also known as c.655G>A), located in coding exon 7 of the TPM1 gene, results from a G to A substitution at nucleotide position 655. The aspartic acid at codon 219 is replaced by asparagine, an amino acid with highly similar properties. This variant was reported in an individual with hypertrophic cardiomyopathy (HCM), as well as in one individual from an HCM genetic testing cohort; however, clinical details were limited in both cases (Coppini R et al. J. Am. Coll. Cardiol., 2014 Dec;64:2589-2600; Walsh R et al. Genet. Med., 2017 02;19:192-203). 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	0.55
CardioboostCm	Pathogenic	0.99
BayesDel_addAF	Pathogenic	0.24	D
BayesDel_noAF	Uncertain	0.10
CADD	Pathogenic	33
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.97	.;.;D;D;.;.;.;.;.;.;D;.;.;.;D;D
Eigen	Pathogenic	0.78
Eigen_PC	Pathogenic	0.80
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Uncertain	0.93	D;D;D;D;D;D;D;D;D;D;D;D;D;D;D;D
M_CAP	Pathogenic	0.51	D
MetaRNN	Pathogenic	0.84	D;D;D;D;D;D;D;D;D;D;D;D;D;D;D;D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Pathogenic	3.7	H;H;H;.;H;H;H;H;.;.;.;.;.;.;.;.
PrimateAI	Pathogenic	0.80	T
PROVEAN	Uncertain	-3.7	D;D;D;D;D;D;D;D;.;D;D;.;D;D;D;D
REVEL	Pathogenic	0.91
Sift	Uncertain	0.0010	D;D;D;D;D;D;D;D;.;D;D;.;D;D;D;D
Sift4G	Uncertain	0.018	D;D;T;D;T;T;D;.;.;T;D;.;D;D;D;D
Polyphen		0.26, 0.88, 0.47, 0.82	.;.;B;P;.;.;.;P;.;.;.;.;.;P;.;.
Vest4		0.82
MutPred		0.56		.;.;.;Loss of phosphorylation at Y263 (P = 0.0749);.;.;.;.;.;.;.;.;.;.;.;.;
MVP		0.92
MPC		2.5
ClinPred		1.0	D
GERP RS		5.8
Varity_R		0.88
gMVP		0.92

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.010		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: rs727503518; hg19: chr15-63354429;