rs397516479

Positions:

• chr1-201361950-C-A
• chr1-201361950-C-G

Variant summary

Our verdict is Likely benign. Variant got -3 ACMG points: 2P and 5B. PM1 BP4 BS2

The NM_001276345.2(TNNT2):​c.682G>T​(p.Val228Leu) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000041 in 1,461,892 control chromosomes in the GnomAD database, including 1 homozygotes. 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: 0.0000041 (1 hom.)
• Consequence: TNNT2 NM_001276345.2 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:3
• 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 Likely_benign. 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
• BP4: Computational evidence support a benign effect (MetaRNN=0.39517134).
• BS2: High AC in GnomAdExome4 at 6 AD gene.

Transcripts

RefSeq

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

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD3 exomes AF: 0.0000119 AC: 3 AN: 251490 Hom.: 1 AF XY: 0.0000221 AC XY: 3 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: 0.0000980

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000410 AC: 6 AN: 1461892 Hom.: 1 Cov.: 32 AF XY: 0.00000550 AC XY: 4 AN XY: 727246

Gnomad4 AFR exome AF: 0.0000299

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.0000232

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00

Gnomad4 OTH exome AF: 0.0000497

GnomAD4 genome Cov.: 33

ExAC AF: 0.0000330 AC: 4

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:3

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not specified Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine

Sep 13, 2013

proposed classification - variant undergoing re-assessment, contact laboratory -

Cardiomyopathy Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

CHEO Genetics Diagnostic Laboratory, Children's Hospital of Eastern Ontario

Jun 12, 2023

- -

Hypertrophic cardiomyopathy Uncertain:1

Uncertain significance, no assertion criteria provided

research

Agnes Ginges Centre for Molecular Cardiology, Centenary Institute

Feb 25, 2020

TNNT2 Val218Leu has been previously identified in a HCM proband (Walsh R et al., 2017). The variant is present at a low frequency in the Genome Aggregation Database (MAF= 0.00001, http://gnomad.broadinstitute.org/). In silico tools predict the variant to be benign (SIFT, Polyphen-2, MutationTaster). We have identified this variant in a male patient with HCM and no family history of disease (Ingles J, et al, 2017). There is limited evidence to suggest a causative role for this variant, therefore we have classified it 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	-0.12	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	0.47	N
M_CAP	Uncertain	0.14	D
MetaRNN	Benign	0.40	T;T;T;T;T;T;T;T;T;T;T
MetaSVM	Benign	-0.63	T
MutationTaster	Benign	0.86	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		0.29	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;