rs876657662

chr15-63060872-G-A

Variant summary

Our verdict is Likely pathogenic. Variant got 9 ACMG points: 9P and 0B. PM1 PM2 PP2 PP3_Moderate PP5_Moderate

The NM_001018005.2(TPM1):c.496G>A(p.Ala166Thr) 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 Likely pathogenic (★). Synonymous variant affecting the same amino acid position (i.e. A166A) has been classified as Uncertain significance.

• Frequency: Genomes: not found (cov: 32)
• Consequence: TPM1 NM_001018005.2 missense
• Clinical Significance: Likely pathogenic criteria provided, single submitter P:1
• 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 9 ACMG points.

• PM1: In a hotspot region, there are 4 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 5 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, 0.896
• PP5: Variant 15-63060872-G-A is Pathogenic according to our data. Variant chr15-63060872-G-A is described in ClinVar as [Likely_pathogenic]. Clinvar id is 228297.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
TPM1	NM_001018005.2	c.496G>A	p.Ala166Thr	missense_variant	5/10	ENST00000403994.9

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
TPM1	ENST00000403994.9	c.496G>A	p.Ala166Thr	missense_variant	5/10	1	NM_001018005.2	A1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 32

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:1

Revision: criteria provided, single submitter

Submissions by phenotype

Primary dilated cardiomyopathy Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine

Mar 16, 2016

The p.Ala166Thr variant in TPM1 has been reported by our laboratory to have appa rently occurred de novo in one child with DCM. It has not been identified in lar ge population studies. Alanine (Ala) at position 166 of the TPM1 protein is high ly conserved in mammals and across evolutionarily distant species and the change to threonine (Thr) was predicted to be pathogenic using a computational tool cl inically validated by our laboratory. This tool's pathogenic prediction is estim ated to be correct 94% of the time (Jordan 2011). In summary, although additiona l studies are required to fully establish its clinical significance, this varian t is likely pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.76
CardioboostCm	Pathogenic	0.99
BayesDel_addAF	Pathogenic	0.55	D
BayesDel_noAF	Pathogenic	0.55
Cadd	Pathogenic	32
Dann	Uncertain	0.99
Eigen	Pathogenic	0.77
Eigen_PC	Pathogenic	0.79
FATHMM_MKL	Pathogenic	0.97	D
LIST_S2	Benign	0.83	T;T;T;T;T;T;T;T;T;T;T;T;T;T;T;T
M_CAP	Pathogenic	0.55	D
MetaRNN	Pathogenic	0.90	D;D;D;D;D;D;D;D;D;D;D;D;D;D;D;D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Uncertain	2.9	M;M;M;.;M;M;M;M;.;.;.;.;.;.;.;.
MutationTaster	Benign	1.0	D;D;D;D;D;D;D;D;D;D;D;D;D
PrimateAI	Pathogenic	0.91	D
PROVEAN	Uncertain	-3.5	D;D;D;D;D;D;D;.;.;D;D;.;D;D;D;D
REVEL	Pathogenic	0.85
Sift	Uncertain	0.011	D;D;D;D;D;D;D;.;.;D;D;.;D;D;D;D
Sift4G	Benign	0.086	T;T;T;T;T;T;T;.;.;T;T;.;T;T;T;D
Polyphen		0.97, 1.0, 0.98, 0.29	.;.;D;D;.;.;.;D;.;.;.;.;.;B;.;.
Vest4		0.83
MutPred		0.69		.;.;.;Gain of phosphorylation at A208 (P = 0.0245);.;.;.;.;.;.;.;.;.;.;.;.;
MVP		0.97
MPC		2.4
ClinPred		0.98	D
GERP RS		5.6
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.68
gMVP		0.87

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: rs876657662; hg19: chr15-63353071;