rs397516364

chr15-63042852-T-Achr15-63042852-T-G

Variant summary

Our verdict is Likely pathogenic. Variant got 9 ACMG points: 9P and 0B. PM1 PM2 PM5 PP2 PP3_Moderate

The NM_001018005.2(TPM1):c.23T>A(p.Met8Lys) 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. 13/22 in silico tools predict a damaging 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. M8R) has been classified as Likely pathogenic.

• Frequency: Genomes: not found (cov: 33)
• Consequence: TPM1 NM_001018005.2 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 7.72

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 hotspot region, there are 3 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
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr15-63042852-T-G is described in ClinVar as [Likely_pathogenic]. Clinvar id is 43406.Status of the report is no_assertion_criteria_provided, 0 stars.
• PP2: Missense variant where missense usually causes diseases, TPM1
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.868

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
TPM1	NM_001018005.2	c.23T>A	p.Met8Lys	missense_variant	1/10	ENST00000403994.9

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
TPM1	ENST00000403994.9	c.23T>A	p.Met8Lys	missense_variant	1/10	1	NM_001018005.2	A1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 33

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Hypertrophic cardiomyopathy Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

Oct 19, 2020

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. 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"). This variant has not been reported in the literature in individuals with TPM1-related conditions. This variant is not present in population databases (ExAC no frequency). This sequence change replaces methionine with lysine at codon 8 of the TPM1 protein (p.Met8Lys). The methionine residue is moderately conserved and there is a moderate physicochemical difference between methionine and lysine. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.99
CardioboostCm	Pathogenic	0.99
BayesDel_addAF	Pathogenic	0.44	D
BayesDel_noAF	Pathogenic	0.40
Cadd	Pathogenic	33
Dann	Uncertain	0.99
Eigen	Pathogenic	0.85
Eigen_PC	Pathogenic	0.75
FATHMM_MKL	Uncertain	0.89	D
LIST_S2	Pathogenic	0.98	D;D;D;.;D;D;D;D;D;D;D
M_CAP	Pathogenic	0.96	D
MetaRNN	Pathogenic	0.87	D;D;D;D;D;D;D;D;D;D;D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Pathogenic	3.9	H;H;.;.;H;.;H;H;H;H;.
MutationTaster	Benign	1.0	D;D;D;D;D;D;D;D
PrimateAI	Pathogenic	0.92	D
PROVEAN	Uncertain	-3.3	D;D;.;D;D;D;D;D;D;.;.
REVEL	Pathogenic	0.89
Sift	Pathogenic	0.0	D;D;.;D;D;D;D;D;D;.;.
Sift4G	Pathogenic	0.0010	D;D;D;D;D;D;D;D;D;.;.
Polyphen		1.0, 1.0, 1.0	.;.;.;.;D;D;.;.;.;D;.
Vest4		0.88
MutPred		0.36		Gain of solvent accessibility (P = 0.012);Gain of solvent accessibility (P = 0.012);Gain of solvent accessibility (P = 0.012);Gain of solvent accessibility (P = 0.012);Gain of solvent accessibility (P = 0.012);Gain of solvent accessibility (P = 0.012);Gain of solvent accessibility (P = 0.012);Gain of solvent accessibility (P = 0.012);Gain of solvent accessibility (P = 0.012);Gain of solvent accessibility (P = 0.012);Gain of solvent accessibility (P = 0.012);
MVP		0.93
MPC		3.1
ClinPred		1.0	D
GERP RS		4.5
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.97
gMVP		1.0

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: rs397516364; hg19: chr15-63335051;