rs199476307

Positions:

• chr15-63044121-A-C
• chr15-63044121-A-G

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.209A>C​(p.Lys70Thr) 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 Uncertain significance (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. K70R) has been classified as Uncertain significance.

• Frequency: Genomes: not found (cov: 32)
• Consequence: TPM1 NM_001018005.2 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2 O:1
• Conservation: PhyloP100: 8.95

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, 12 uncertain in NM_001018005.2
• PM2: Very rare variant in population databases, with high coverage
• PP2: Missense variant in gene, where missense usually causes diseases (based on misZ statistic), TPM1. . Gene score misZ 2.8677 (greater than the threshold 3.09). Trascript score misZ 3.9402 (greater than threshold 3.09). GenCC has associacion of gene with 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, 0.864

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
TPM1	NM_001018005.2	c.209A>C	p.Lys70Thr	missense_variant	2/10	ENST00000403994.9

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
TPM1	ENST00000403994.9	c.209A>C	p.Lys70Thr	missense_variant	2/10	1	NM_001018005.2	A1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 33

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2 Other:1

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Hypertrophic cardiomyopathy Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

Jun 08, 2022

This sequence change replaces lysine, which is basic and polar, with threonine, which is neutral and polar, at codon 70 of the TPM1 protein (p.Lys70Thr). This variant is not present in population databases (gnomAD no frequency). This missense change has been observed in individual(s) with mild hypertrophic cardiomyopathy (PMID: 8774330). ClinVar contains an entry for this variant (Variation ID: 31878). 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: "Benign"; Align-GVGD: "Class C0"). Experimental studies have shown that this missense change affects TPM1 function (PMID: 12900417, 15479242, 25241052). 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. -

Cardiovascular phenotype Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Jun 14, 2019

The c.209A>C (p.K70T) alteration is located in exon 2 (coding exon 2) of the TPM1 gene. This alteration results from a A to C substitution at nucleotide position 209, causing the lysine (K) at amino acid position 70 to be replaced by a threonine (T). Based on insufficient or conflicting evidence, the clinical significance of this alteration remains unclear. -

not provided Other:1

not provided, no classification provided

curation

Leiden Muscular Dystrophy (TPM1)

Apr 15, 2012

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.21
CardioboostCm	Pathogenic	0.95
BayesDel_addAF	Pathogenic	0.46	D
BayesDel_noAF	Pathogenic	0.42
CADD	Pathogenic	27
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.50	.;.;D;D;D;.;.
Eigen	Uncertain	0.48
Eigen_PC	Uncertain	0.56
FATHMM_MKL	Uncertain	0.96	D
LIST_S2	Pathogenic	0.99	D;D;D;D;D;D;D
M_CAP	Pathogenic	0.65	D
MetaRNN	Pathogenic	0.86	D;D;D;D;D;D;D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Pathogenic	3.3	M;M;.;M;.;M;.
MutationTaster	Benign	1.0	D;D;D;D;D;D;D;D
PROVEAN	Uncertain	-3.2	D;D;.;D;D;D;.
REVEL	Pathogenic	0.87
Sift	Uncertain	0.0030	D;D;.;D;D;D;.
Sift4G	Uncertain	0.015	D;D;D;D;D;D;.
Polyphen		0.029, 0.14	.;.;.;B;B;.;.
Vest4		0.79
MutPred		0.61		.;.;.;.;Loss of ubiquitination at K112 (P = 0.0012);.;.;
MVP		0.98
MPC		2.1
ClinPred		0.98	D
GERP RS		5.7
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.73
gMVP		0.94

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: rs199476307; hg19: chr15-63336320;