2-178576942-G-A

Variant names:

• chr2-178576942-G-A
• rs727504692
• NM_001267550.2:c.69393C>T

Variant summary

Our verdict is Benign. The variant received -13 ACMG points: 0P and 13B. BP4_Strong BP6_Very_Strong BP7

The NM_001267550.2(TTN):​c.69393C>T​(p.Val23131Val) variant causes a synonymous change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000754 in 1,458,532 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 Likely benign (★★). Synonymous variant affecting the same amino acid position (i.e. V23131V) has been classified as Likely benign.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000075 (0 hom.)
• Consequence: TTN NM_001267550.2 synonymous
• Clinical Significance: Likely benign criteria provided, multiple submitters, no conflicts B:3
• Conservation: PhyloP100: 1.90

Genes affected

TTN (HGNC:12403): (titin) This gene encodes a large abundant protein of striated muscle. The product of this gene is divided into two regions, a N-terminal I-band and a C-terminal A-band. The I-band, which is the elastic part of the molecule, contains two regions of tandem immunoglobulin domains on either side of a PEVK region that is rich in proline, glutamate, valine and lysine. The A-band, which is thought to act as a protein-ruler, contains a mixture of immunoglobulin and fibronectin repeats, and possesses kinase activity. An N-terminal Z-disc region and a C-terminal M-line region bind to the Z-line and M-line of the sarcomere, respectively, so that a single titin molecule spans half the length of a sarcomere. Titin also contains binding sites for muscle associated proteins so it serves as an adhesion template for the assembly of contractile machinery in muscle cells. It has also been identified as a structural protein for chromosomes. Alternative splicing of this gene results in multiple transcript variants. Considerable variability exists in the I-band, the M-line and the Z-disc regions of titin. Variability in the I-band region contributes to the differences in elasticity of different titin isoforms and, therefore, to the differences in elasticity of different muscle types. Mutations in this gene are associated with familial hypertrophic cardiomyopathy 9, and autoantibodies to titin are produced in patients with the autoimmune disease scleroderma. [provided by RefSeq, Feb 2012]

TTN-AS1 (HGNC:44124): (TTN antisense RNA 1) This gene encodes a non-coding RNA transcribed from the opposite strand to the titin gene. [provided by RefSeq, Aug 2016]

ENSG00000271011 (HGNC:):

ACMG classification

Our verdict: Benign. The variant received -13 ACMG points.

• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.49).
• BP6: Variant 2-178576942-G-A is Benign according to our data. Variant chr2-178576942-G-A is described in ClinVar as [Likely_benign]. Clinvar id is 509655.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.
• BP7: Synonymous conserved (PhyloP=1.9 with no splicing effect.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
TTN	NM_001267550.2	c.69393C>T	p.Val23131Val	synonymous_variant	Exon 324 of 363	ENST00000589042.5	NP_001254479.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
TTN	ENST00000589042.5	c.69393C>T	p.Val23131Val	synonymous_variant	Exon 324 of 363	5	NM_001267550.2	ENSP00000467141.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD2 exomes AF: 0.0000162 AC: 4 AN: 246678 AF XY: 0.0000149

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.000117

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000754 AC: 11 AN: 1458532 Hom.: 0 Cov.: 35 AF XY: 0.00000689 AC XY: 5 AN XY: 725246

African (AFR) AF: 0.00 AC: 0 AN: 33262

American (AMR) AF: 0.000226 AC: 10 AN: 44318

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26048

East Asian (EAS) AF: 0.00 AC: 0 AN: 39644

South Asian (SAS) AF: 0.0000117 AC: 1 AN: 85802

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53348

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5744

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 1110142

Other (OTH) AF: 0.00 AC: 0 AN: 60224

GnomAD4 genome Cov.: 32

Alfa AF: 0.00 Hom.: 0

Bravo AF: 0.0000264

ClinVar

Significance: Likely benign

Submissions summary: Benign:3

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

TTN-related disorder Benign:1

Aug 02, 2019

PreventionGenetics, part of Exact Sciences

Significance: Likely benign

Review Status: no assertion criteria provided

Collection Method: clinical testing

This variant is classified as likely benign based on ACMG/AMP sequence variant interpretation guidelines (Richards et al. 2015 PMID: 25741868, with internal and published modifications). -

Autosomal recessive limb-girdle muscular dystrophy type 2J;C1858763:Dilated cardiomyopathy 1G Benign:1

Jun 15, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Likely benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

not provided Benign:1

Aug 05, 2020

GeneDx

Significance: Likely benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.49
CADD	Benign	1.0
DANN	Benign	0.70
PhyloP100		1.9
Mutation Taster		=78/22	polymorphism

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.060		Details are displayed if max score is > 0.2

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

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Other links and lift over

dbSNP: rs727504692; hg19: chr2-179441669; COSMIC: COSV59884323; COSMIC: COSV59884323;