1-201361950-C-G

Position:

• chr1-201361950-C-G

Variant summary

Our verdict is Uncertain significance. Variant got 3 ACMG points: 4P and 1B. PM1 PM2 BP4

The NM_001276345.2(TNNT2):​c.682G>C​(p.Val228Leu) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000000684 in 1,461,892 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★★). Another nucleotide change resulting in same amino acid change has been previously reported as Uncertain significancein ClinVar.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: TNNT2 NM_001276345.2 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: 2.34

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]

ACMG classification

Verdict is Uncertain_significance. Variant got 3 ACMG points.

• PM1: In a chain Troponin T, cardiac muscle (size 296) in uniprot entity TNNT2_HUMAN there are 174 pathogenic changes around while only 18 benign (91%) in NM_001276345.2
• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.4229712).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
TNNT2	NM_001276345.2	c.682G>C	p.Val228Leu	missense_variant	14/17	ENST00000656932.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
TNNT2	ENST00000656932.1	c.682G>C	p.Val228Leu	missense_variant	14/17		NM_001276345.2	A2

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD3 exomes AF: 0.00000398 AC: 1 AN: 251490 Hom.: 0 AF XY: 0.00 AC XY: 0 AN XY: 135920

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad SAS exome AF: 0.0000327

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461892 Hom.: 0 Cov.: 32 AF XY: 0.00 AC XY: 0 AN XY: 727246

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00

Gnomad4 OTH exome AF: 0.0000166

GnomAD4 genome Cov.: 33

Bravo AF: 0.00000378

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Cardiomyopathy Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Color Diagnostics, LLC DBA Color Health

Jun 13, 2023

This missense variant replaces valine with leucine at codon 218 of the TNNT2 protein. Computational prediction suggests that this variant may not impact protein structure and function (internally defined REVEL score threshold <= 0.5, PMID: 27666373). To our knowledge, functional studies have not been reported for this variant. This variant has been reported in two individuals affected with hypertrophic cardiomyopathy (PMID: 25611685, 27532257, 28408708, 28790153). This variant has been identified in 1/251490 chromosomes in the general population by the Genome Aggregation Database (gnomAD). The available evidence is insufficient to determine the role of this variant in disease conclusively. Therefore, this variant is classified as a Variant of Uncertain Significance. -

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

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

Aug 28, 2021

This sequence change replaces valine with leucine at codon 218 of the TNNT2 protein (p.Val218Leu). The valine residue is weakly conserved and there is a small physicochemical difference between valine and leucine. This variant is not present in population databases (ExAC no frequency). This missense change has been observed in individual(s) with hypertrophic cardiomyopathy (PMID: 28790153). Algorithms developed to predict the effect of missense changes on protein structure and function (SIFT, PolyPhen-2, Align-GVGD) all suggest that this variant is likely to be tolerated. 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. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.25
CardioboostCm	Benign	0.074
BayesDel_addAF	Benign	-0.025	T
BayesDel_noAF	Benign	-0.18
CADD	Uncertain	25
DANN	Uncertain	0.98
Eigen	Benign	-0.21
Eigen_PC	Benign	-0.076
FATHMM_MKL	Benign	0.16	N
M_CAP	Uncertain	0.13	D
MetaRNN	Benign	0.42	T;T;T;T;T;T;T;T;T;T;T
MetaSVM	Benign	-0.63	T
MutationTaster	Benign	0.93	N;N;N;N;N;N;N;N;N;N
PrimateAI	Uncertain	0.54	T
PROVEAN	Benign	-1.0	N;N;.;.;.;.;.;.;N;N;N
REVEL	Uncertain	0.37
Sift	Uncertain	0.0020	D;D;.;.;.;.;.;.;D;D;D
Sift4G	Uncertain	0.0090	D;D;D;D;D;T;D;T;D;D;.
Polyphen		0.075	.;.;.;.;B;.;.;.;.;.;.
Vest4		0.34
MutPred		0.56		.;.;.;.;Loss of methylation at K227 (P = 0.0342);.;.;.;.;.;.;
MVP		0.82
MPC		0.55
ClinPred		0.36	T
GERP RS		3.5
Varity_R		0.29
gMVP		0.73

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: rs397516479; hg19: chr1-201331078;