NM_001077653.2:c.818C>T

Variant names:

• chr7-35231576-G-A
• rs1554286367
• NM_001077653.2:c.818C>T

Variant summary

Our verdict is Uncertain significance. Variant got 4 ACMG points: 4P and 0B. PM2 PP3_Moderate

The NM_001077653.2(TBX20):​c.818C>T​(p.Thr273Met) 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. 13/21 in silico tools predict a damaging outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★★).

• Frequency: Genomes: not found (cov: 32)
• Consequence: TBX20 NM_001077653.2 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:4
• Conservation: PhyloP100: 10.0

Genes affected

TBX20 (HGNC:11598): (T-box transcription factor 20) This gene encodes a T-box family member. The T-box family members share a common DNA binding domain, termed the T-box, and they are transcription factors involved in the regulation of developmental processes. This gene is essential for heart development. Mutations in this gene are associated with diverse cardiac pathologies, including defects in septation, valvulogenesis and cardiomyopathy. Alternatively spliced transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq, Oct 2009]

ACMG classification

Verdict is Uncertain_significance. Variant got 4 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.9

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
TBX20	NM_001077653.2	c.818C>T	p.Thr273Met	missense_variant	Exon 6 of 8	ENST00000408931.4	NP_001071121.1
TBX20	NM_001166220.1	c.818C>T	p.Thr273Met	missense_variant	Exon 6 of 6		NP_001159692.1
TBX20	XM_017012456.2	c.221C>T	p.Thr74Met	missense_variant	Exon 4 of 6		XP_016867945.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
TBX20	ENST00000408931.4	c.818C>T	p.Thr273Met	missense_variant	Exon 6 of 8	1	NM_001077653.2	ENSP00000386170.3
TBX20	ENST00000492961.1	n.829C>T		non_coding_transcript_exon_variant	Exon 6 of 6	1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 29

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:4

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not provided Uncertain:2

Jul 22, 2019

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, which includes protein predictors and evolutionary conservation, supports a deleterious effect; Has not been previously published as pathogenic or benign to our knowledge -

Oct 28, 2023

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces threonine, which is neutral and polar, with methionine, which is neutral and non-polar, at codon 273 of the TBX20 protein (p.Thr273Met). This variant is not present in population databases (gnomAD no frequency). This variant has not been reported in the literature in individuals affected with TBX20-related conditions. ClinVar contains an entry for this variant (Variation ID: 519119). 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 TBX20 protein function with a positive predictive value of 80%. 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. -

Atrial septal defect 4 Uncertain:1

Oct 31, 2018

Fulgent Genetics, Fulgent Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Cardiovascular phenotype Uncertain:1

Apr 20, 2024

Ambry Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The p.T273M variant (also known as c.818C>T), located in coding exon 6 of the TBX20 gene, results from a C to T substitution at nucleotide position 818. The threonine at codon 273 is replaced by methionine, an amino acid with similar properties. This variant was not reported in population based cohorts in the following databases: Database of Single Nucleotide Polymorphisms (dbSNP), NHLBI Exome Sequencing Project (ESP), and 1000 Genomes Project. In the ESP, this variant was not observed in 6503 samples (13006 alleles) with coverage at this position. This amino acid position is highly conserved in available vertebrate species. In addition, this alteration is predicted to be deleterious by in silico analysis. Since supporting evidence is limited at this time, the clinical significance of this variant remains unclear. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	1.0
BayesDel_addAF	Pathogenic	0.45	D
BayesDel_noAF	Pathogenic	0.41
CADD	Pathogenic	33
DANN	Pathogenic	1.0
DEOGEN2	Pathogenic	0.96	D
Eigen	Pathogenic	1.1
Eigen_PC	Pathogenic	0.95
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Pathogenic	0.99	D
M_CAP	Pathogenic	0.72	D
MetaRNN	Pathogenic	0.90	D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Pathogenic	4.0	H
PrimateAI	Pathogenic	0.92	D
PROVEAN	Pathogenic	-5.9	D
REVEL	Pathogenic	0.87
Sift	Pathogenic	0.0	D
Sift4G	Pathogenic	0.0010	D
Polyphen		1.0	D
Vest4		0.60
MVP		0.99
MPC		1.6
ClinPred		1.0	D
GERP RS		5.5
Varity_R		0.93
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: rs1554286367; hg19: chr7-35271188;