NM_001276345.2:c.445C>G

Variant names:

• chr1-201364342-G-C
• rs397516465
• NM_001276345.2:c.445C>G

Variant summary

Our verdict is Pathogenic. The variant received 10 ACMG points: 10P and 0B. PM1 PM2 PM5 PP3_Moderate PP5_Moderate

The NM_001276345.2(TNNT2):​c.445C>G​(p.Arg149Gly) variant causes a missense change involving the alteration of a non-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. R149H) has been classified as Pathogenic.

• Frequency: Genomes: not found (cov: 33)
• Consequence: TNNT2 NM_001276345.2 missense
• Clinical Significance: Likely pathogenic criteria provided, single submitter P:1
• Conservation: PhyloP100: 2.65
• Publications: 0 publications found

Genes affected

TNNT2 (HGNC:11949): (troponin T2, cardiac type) This gene encodes the cardiac isoform of troponin T. The encoded protein is the tropomyosin-binding subunit of the troponin complex, which is located on the thin filament of striated muscles and regulates muscle contraction in response to alterations in intracellular calcium ion concentration. Mutations in this gene have been associated with familial hypertrophic cardiomyopathy as well as with dilated cardiomyopathy. [provided by RefSeq, May 2022]

TNNT2 Gene-Disease associations (from GenCC):

• dilated cardiomyopathy

  Inheritance: AD Classification: DEFINITIVE Submitted by: ClinGen
• dilated cardiomyopathy 1D

  Inheritance: AD Classification: DEFINITIVE, STRONG Submitted by: Labcorp Genetics (formerly Invitae), Ambry Genetics
• hypertrophic cardiomyopathy

  Inheritance: AD Classification: DEFINITIVE Submitted by: ClinGen
• hypertrophic cardiomyopathy 2

  Inheritance: AD Classification: DEFINITIVE, STRONG Submitted by: PanelApp Australia, G2P, Ambry Genetics, Labcorp Genetics (formerly Invitae)
• hypertrophic cardiomyopathy 3

  Inheritance: AD Classification: DEFINITIVE Submitted by: G2P
• cardiomyopathy, familial restrictive, 3

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

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• familial isolated restrictive cardiomyopathy

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

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• cardiomyopathy

  Inheritance: AR Classification: LIMITED Submitted by: Ambry Genetics
• arrhythmogenic right ventricular cardiomyopathy

  Inheritance: AD Classification: NO_KNOWN Submitted by: ClinGen

ENSG00000286600 (HGNC:):

ACMG classification

Our verdict: Pathogenic. The variant received 10 ACMG points.

• PM1: In a hotspot region, there are 13 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 15 uncertain in NM_001276345.2
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr1-201364341-C-T is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 43642.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.892
• PP5: Variant 1-201364342-G-C is Pathogenic according to our data. Variant chr1-201364342-G-C is described in ClinVar as Likely_pathogenic. ClinVar VariationId is 2115456.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
TNNT2	NM_001276345.2	c.445C>G	p.Arg149Gly	missense_variant	Exon 11 of 17	ENST00000656932.1	NP_001263274.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
TNNT2	ENST00000656932.1	c.445C>G	p.Arg149Gly	missense_variant	Exon 11 of 17		NM_001276345.2	ENSP00000499593.1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 33

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:1

Revision: criteria provided, single submitter

Submissions by phenotype

Dilated cardiomyopathy 1D;C1861864:Hypertrophic cardiomyopathy 2;C2676271:Cardiomyopathy, familial restrictive, 3 Pathogenic:1

Nov 29, 2022

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

In summary, the currently available evidence indicates that the variant is pathogenic, but additional data are needed to prove that conclusively. Therefore, this variant has been classified as Likely Pathogenic. This variant disrupts the p.Arg139 amino acid residue in TNNT2. Other variant(s) that disrupt this residue have been determined to be pathogenic (PMID: 20973921, 27532257; Invitae). This suggests that this residue is clinically significant, and that variants that disrupt this residue are likely to be disease-causing. Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is expected to disrupt TNNT2 protein function. This variant has not been reported in the literature in individuals affected with TNNT2-related conditions. This variant is not present in population databases (gnomAD no frequency). This sequence change replaces arginine, which is basic and polar, with glycine, which is neutral and non-polar, at codon 139 of the TNNT2 protein (p.Arg139Gly). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.87
CardioboostCm	Uncertain	0.80
BayesDel_addAF	Pathogenic	0.35	D
BayesDel_noAF	Pathogenic	0.26
CADD	Pathogenic	31
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.97	.;.;.;.;D;.;.;.;.;.;D;.
Eigen	Uncertain	0.64
Eigen_PC	Uncertain	0.53
FATHMM_MKL	Uncertain	0.94	D
LIST_S2	Uncertain	0.97	.;D;D;D;D;D;D;.;.;D;.;.
M_CAP	Pathogenic	0.93	D
MetaRNN	Pathogenic	0.89	D;D;D;D;D;D;D;D;D;D;D;D
MetaSVM	Pathogenic	0.94	D
MutationAssessor	Pathogenic	3.1	.;.;.;.;M;.;.;.;.;.;.;.
PhyloP100		2.6
PrimateAI	Uncertain	0.75	T
PROVEAN	Pathogenic	-6.1	D;D;D;.;D;D;D;.;D;D;D;D
REVEL	Pathogenic	0.87
Sift	Pathogenic	0.0	D;D;D;.;D;D;D;.;D;D;D;D
Sift4G	Pathogenic	0.0010	D;D;D;D;D;D;D;D;D;D;.;D
Polyphen		1.0, 0.99	.;.;.;.;D;.;.;.;.;.;D;.
Vest4		0.80
MutPred		0.51		.;.;.;.;Loss of stability (P = 0.2099);.;.;.;.;.;.;Loss of stability (P = 0.2099);
MVP		0.98
MPC		1.4
ClinPred		0.99	D
GERP RS		4.3
Varity_R		0.91
gMVP		0.99
Mutation Taster		=24/76	disease causing

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: rs397516465; hg19: chr1-201333470;