NM_001276345.2:c.593T>C

Variant names:

• chr1-201363303-A-G
• rs878854148
• NM_001276345.2:c.593T>C

Variant summary

Our verdict is Uncertain significance. The variant received 2 ACMG points: 2P and 0B. PM2

The NM_001276345.2(TNNT2):​c.593T>C​(p.Ile198Thr) variant causes a missense change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. 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. I198V) has been classified as Likely benign.

• Frequency: Genomes: not found (cov: 32)
• Consequence: TNNT2 NM_001276345.2 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:5
• Conservation: PhyloP100: 8.48
• Publications: 3 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: Uncertain_significance. The variant received 2 ACMG points.

• PM2: Very rare variant in population databases, with high coverage

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_001276345.2. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	TNNT2	NM_001276345.2	MANE Select	c.593T>C	p.Ile198Thr	missense	Exon 12 of 17	NP_001263274.1
	TNNT2	NM_000364.4		c.593T>C	p.Ile198Thr	missense	Exon 12 of 16	NP_000355.2
	TNNT2	NM_001406723.1		c.593T>C	p.Ile198Thr	missense	Exon 12 of 16	NP_001393652.1

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	TNNT2	ENST00000656932.1	MANE Select	c.593T>C	p.Ile198Thr	missense	Exon 12 of 17	ENSP00000499593.1
	TNNT2	ENST00000367322.6	TSL:1	c.560T>C	p.Ile187Thr	missense	Exon 11 of 15	ENSP00000356291.2
	TNNT2	ENST00000367320.6	TSL:1	c.473T>C	p.Ile158Thr	missense	Exon 11 of 15	ENSP00000356289.2

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:5

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Dilated cardiomyopathy 1D Uncertain:1

Apr 11, 2023

Genome-Nilou Lab

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

not provided Uncertain:1

May 18, 2020

GeneDx

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Not observed in large population cohorts (Lek et al., 2016); In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; Has not been previously published as pathogenic or benign to our knowledge

Cardiomyopathy, familial restrictive, 3 Uncertain:1

Apr 11, 2023

Genome-Nilou Lab

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Hypertrophic cardiomyopathy 2 Uncertain:1

Apr 11, 2023

Genome-Nilou Lab

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

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

Dec 05, 2016

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

In summary, this is a novel missense change with uncertain impact on protein function. It has been classified as a Variant of Uncertain Significance. Algorithms developed to predict the effect of missense changes on protein structure and function do not agree on the potential impact of this missense change (SIFT: "Tolerated"; PolyPhen-2: "Possibly Damaging"; Align-GVGD: "Class C0"). This variant is not present in population databases (ExAC no frequency) and has not been reported in the literature in individuals with a TNNT2-related disease. This sequence change replaces isoleucine with threonine at codon 188 of the TNNT2 protein (p.Ile188Thr). The isoleucine residue is weakly conserved and there is a moderate physicochemical difference between isoleucine and threonine.

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.96
CardioboostCm	Benign	0.061
BayesDel_addAF	Pathogenic	0.29	D
BayesDel_noAF	Pathogenic	0.18
CADD	Uncertain	25
DANN	Uncertain	0.99
DEOGEN2	Uncertain	0.68	D
Eigen	Benign	0.091
Eigen_PC	Uncertain	0.24
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.97	D
M_CAP	Pathogenic	0.37	D
MetaRNN	Uncertain	0.60	D
MetaSVM	Benign	-0.53	T
MutationAssessor	Benign	0.69	N
PhyloP100		8.5
PrimateAI	Pathogenic	0.81	D
PROVEAN	Benign	-1.6	N
REVEL	Uncertain	0.53
Sift	Uncertain	0.0010	D
Sift4G	Benign	0.13	T
Polyphen		0.48	P
Vest4		0.64
MutPred		0.47		Loss of catalytic residue at I198 (P = 0.0171)
MVP		0.95
MPC		1.1
ClinPred		0.81	D
GERP RS		4.9
Varity_R		0.13
gMVP		0.63
Mutation Taster		=43/57	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: rs878854148; hg19: chr1-201332431;