rs727504313

chr15-63057087-G-A

Variant summary

Our verdict is Likely pathogenic. Variant got 7 ACMG points: 7P and 0B. PM1 PM2 PP2 PP3_Moderate

The NM_001018005.2(TPM1):c.343G>A(p.Glu115Lys) 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. 12/21 in silico tools predict a damaging outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars). Synonymous variant affecting the same amino acid position (i.e. E115E) has been classified as Likely benign.

• 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:4
• Conservation: PhyloP100: 10.0

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 7 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_001018005.2
• PM2: Very rare variant in population databases, with high coverage
• PP2: Missense variant where missense usually causes diseases, TPM1
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.929

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
TPM1	NM_001018005.2	c.343G>A	p.Glu115Lys	missense_variant	3/10	ENST00000403994.9

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
TPM1	ENST00000403994.9	c.343G>A	p.Glu115Lys	missense_variant	3/10	1	NM_001018005.2	A1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 33

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:1 Uncertain:4

Revision: criteria provided, conflicting classifications

Submissions by phenotype

Dilated cardiomyopathy 1Y Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Laboratory of Medical Genetics, National & Kapodistrian University of Athens

Oct 01, 2021

PM1, PM2, PP2, PP3 -

not specified Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine

Nov 23, 2018

The p.Glu115Lys variant in TPM1 has been identified in 1 individual with HCM and was absent from large population studies. This variant has also been reported i n ClinVar (Variation ID 177761). Computational prediction tools and conservation analysis suggest that this variant may impact the protein, though this informat ion is not predictive enough to determine pathogenicity. In summary, the clinica l significance of the p.Glu115Lys variant is uncertain. ACMG/AMP Criteria applie d: PM2, PP3. -

Cardiomyopathy Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

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

Jan 08, 2020

- -

not provided Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

GeneDx

Oct 20, 2017

The E115K variant of uncertain significance has been identified in the TPM1 gene. E115K has previously beenreported as a likely pathogenic variant in one individual diagnosed with HCM (Alfares et al., 2015; Walsh et al.,2017), though no specific clinical details or segregation data were provided. The E115K variant is anon-conservative amino acid substitution, which is likely to impact secondary protein structure as these residues differin polarity, charge, size and/or other properties. Moreover, this substitution occurs at a position that is conservedacross species, and in silico analysis predicts this variant is probably damaging to the protein structure/function.However, this variant has not been observed in a significant number of affected individuals and it lacks bothsegregation and functional studies which would further clarify its pathogenicity. -

Hypertrophic cardiomyopathy Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

Dec 10, 2021

This sequence change replaces glutamic acid, which is acidic and polar, with lysine, which is basic and polar, at codon 115 of the TPM1 protein (p.Glu115Lys). This variant is not present in population databases (gnomAD no frequency). This missense change has been observed in individual(s) with hypertrophic cardiomyopathy (PMID: 25611685, 27532257). ClinVar contains an entry for this variant (Variation ID: 177761). Algorithms developed to predict the effect of missense changes on protein structure and function are either unavailable or do not agree on the potential impact of this missense change (SIFT: "Deleterious"; PolyPhen-2: "Probably Damaging"; Align-GVGD: "Class C0"). 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	0.87
CardioboostCm	Pathogenic	1.0
BayesDel_addAF	Pathogenic	0.54	D
BayesDel_noAF	Pathogenic	0.54
Cadd	Pathogenic	33
Dann	Uncertain	1.0
Eigen	Pathogenic	0.86
Eigen_PC	Pathogenic	0.86
FATHMM_MKL	Uncertain	0.96	D
LIST_S2	Uncertain	0.93	D;D;D;D;D;D;D;D;D;D;D;D;D;D;D
M_CAP	Pathogenic	0.61	D
MetaRNN	Pathogenic	0.93	D;D;D;D;D;D;D;D;D;D;D;D;D;D;D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Pathogenic	4.3	H;H;H;.;H;H;H;H;.;.;.;.;.;.;.
MutationTaster	Benign	1.0	D;D;D;D;D;D;D;D;D;D;D;D;D
PrimateAI	Pathogenic	0.84	D
PROVEAN	Uncertain	-3.3	D;D;D;D;D;D;D;.;.;D;D;.;D;D;D
REVEL	Pathogenic	0.85
Sift	Uncertain	0.015	D;D;D;D;D;D;D;.;.;D;D;.;D;D;D
Sift4G	Uncertain	0.054	T;D;D;D;D;D;D;.;.;D;D;.;D;D;D
Polyphen		0.26, 0.87, 0.49, 0.91	.;.;B;P;.;.;.;P;.;.;.;.;.;P;.
Vest4		0.92
MutPred		0.79		.;.;.;Gain of MoRF binding (P = 0.0055);.;.;.;.;.;.;.;.;.;.;.;
MVP		0.97
MPC		2.6
ClinPred		1.0	D
GERP RS		5.7
Varity_R		0.91
gMVP		0.98

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

Publications

LitVar

Other links and lift over

dbSNP: rs727504313; hg19: chr15-63349286;