rs876657662

Variant names:

• chr15-63060872-G-A
• rs876657662
• NM_001018005.2:c.496G>A

Variant summary

Our verdict is Pathogenic. The variant received 10 ACMG points: 10P and 0B. PM1 PM2 PM5 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 (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. A166V) has been classified as Pathogenic.

• 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
• Publications: 1 publications found

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]

TPM1 Gene-Disease associations (from GenCC):

• hypertrophic cardiomyopathy

  Inheritance: AD Classification: DEFINITIVE Submitted by: ClinGen
• hypertrophic cardiomyopathy 3

  Inheritance: AD Classification: DEFINITIVE, STRONG Submitted by: Labcorp Genetics (formerly Invitae), PanelApp Australia, G2P
• dilated cardiomyopathy 1Y

  Inheritance: AD Classification: STRONG Submitted by: Labcorp Genetics (formerly Invitae)
• dilated cardiomyopathy

  Inheritance: AD Classification: MODERATE Submitted by: ClinGen
• familial isolated dilated cardiomyopathy

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• left ventricular noncompaction

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• arrhythmogenic right ventricular cardiomyopathy

  Inheritance: AD Classification: NO_KNOWN Submitted by: ClinGen

ACMG classification

Our verdict: Pathogenic. The variant received 10 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, 6 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 chr15-63060873-C-T is described in ClinVar as [Pathogenic]. Clinvar id is 3340563.Status of the report is criteria_provided_single_submitter, 1 stars.
• 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 rank	MANE	Protein	UniProt
TPM1	NM_001018005.2	c.496G>A	p.Ala166Thr	missense_variant	Exon 5 of 10	ENST00000403994.9	NP_001018005.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
TPM1	ENST00000403994.9	c.496G>A	p.Ala166Thr	missense_variant	Exon 5 of 10	1	NM_001018005.2	ENSP00000385107.4

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 32

Alfa AF: 0.0000431 Hom.: 0

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:1

Revision: criteria provided, single submitter

Submissions by phenotype

Primary dilated cardiomyopathy Pathogenic:1

Mar 16, 2016

Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

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
DEOGEN2	Pathogenic	0.98	.;.;D;D;.;.;.;.;.;.;D;.;.;.;D;D
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;.;.;.;.;.;.;.;.
PhyloP100		10
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
Mutation Taster		=15/85	disease causing (ClinVar)

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

Other links and lift over

dbSNP: rs876657662; hg19: chr15-63353071;