NM_001267550.2:c.50774T>C

Variant names:

• chr2-178611455-A-G
• rs370067597
• NM_001267550.2:c.50774T>C

Variant summary

Our verdict is Likely benign. The variant received -1 ACMG points: 0P and 1B. BP4

The NM_001267550.2(TTN):​c.50774T>C​(p.Val16925Ala) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.000172 in 1,612,800 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 Conflicting classifications of pathogenicity (no stars). Synonymous variant affecting the same amino acid position (i.e. V16925V) has been classified as Likely benign.

• Frequency:
  • Genomes: 𝑓 0.000086 (0 hom., cov: 33)
  • Exomes 𝑓: 0.00018 (0 hom.)
• Consequence: TTN NM_001267550.2 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:11 B:1
• Conservation: PhyloP100: 7.43
• Publications: 1 publications found

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]

ACMG classification

Our verdict: Likely_benign. The variant received -1 ACMG points.

• BP4: Computational evidence support a benign effect (MetaRNN=0.306537).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
TTN	NM_001267550.2	c.50774T>C	p.Val16925Ala	missense_variant	Exon 269 of 363	ENST00000589042.5	NP_001254479.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
TTN	ENST00000589042.5	c.50774T>C	p.Val16925Ala	missense_variant	Exon 269 of 363	5	NM_001267550.2	ENSP00000467141.1

Frequencies

GnomAD3 genomes AF: 0.0000855 AC: 13 AN: 151978 Hom.: 0 Cov.: 33

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.000191

Gnomad OTH AF: 0.00

GnomAD2 exomes AF: 0.0000364 AC: 9 AN: 247360 AF XY: 0.0000298

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 FIN exome AF: 0.00

Gnomad NFE exome AF: 0.0000807

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.000181 AC: 265 AN: 1460822 Hom.: 0 Cov.: 33 AF XY: 0.000168 AC XY: 122 AN XY: 726710

African (AFR) AF: 0.00 AC: 0 AN: 33412

American (AMR) AF: 0.00 AC: 0 AN: 44680

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26114

East Asian (EAS) AF: 0.00 AC: 0 AN: 39544

South Asian (SAS) AF: 0.00 AC: 0 AN: 86242

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53370

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5754

European-Non Finnish (NFE) AF: 0.000223 AC: 248 AN: 1111398

Other (OTH) AF: 0.000282 AC: 17 AN: 60308

GnomAD4 genome AF: 0.0000855 AC: 13 AN: 151978 Hom.: 0 Cov.: 33 AF XY: 0.0000674 AC XY: 5 AN XY: 74216

African (AFR) AF: 0.00 AC: 0 AN: 41428

American (AMR) AF: 0.00 AC: 0 AN: 15252

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 3468

East Asian (EAS) AF: 0.00 AC: 0 AN: 5126

South Asian (SAS) AF: 0.00 AC: 0 AN: 4832

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10620

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 316

European-Non Finnish (NFE) AF: 0.000191 AC: 13 AN: 67934

Other (OTH) AF: 0.00 AC: 0 AN: 2090

Alfa AF: 0.000195 Hom.: 0

Bravo AF: 0.0000793

TwinsUK AF: 0.00 AC: 0

ALSPAC AF: 0.000259 AC: 1

ESP6500AA AF: 0.00 AC: 0

ESP6500EA AF: 0.000119 AC: 1

ExAC AF: 0.0000331 AC: 4

EpiCase AF: 0.000273

EpiControl AF: 0.000119

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:11 Benign:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

not provided Uncertain:2 Benign:1

Nov 28, 2022

Revvity Omics, Revvity

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Sep 08, 2020

GeneDx

Significance: Likely benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant is associated with the following publications: (PMID: 31983221) -

Jul 01, 2023

CeGaT Center for Human Genetics Tuebingen

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

TTN: PM2, BP1 -

not specified Uncertain:2

Apr 18, 2015

Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The p.Val14357Ala variant in TTN has been identified by our laboratory in 1 adul t with HCM and AFib; however, this individual also carried a pathogenic MYH7 var iant. The p.Val14357Ala variant has also been identified in 4/66492 European chr omosomes by the Exome Aggregation Consortium (ExAC, http://exac.broadinstitute.o rg; dbSNP rs370067597). Computational prediction tools and conservation analysis do not provide strong support for or against an impact to the protein. In summa ry, the clinical significance of the p.Val14357Ala variant is uncertain. -

Oct 21, 2024

Women's Health and Genetics/Laboratory Corporation of America, LabCorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Variant summary: TTN c.43070T>C (p.Val14357Ala), also reported as c.50774T>C p.Val16925Ala, results in a non-conservative amino acid change located in the I-band of the encoded protein sequence. Three of five in-silico tools predict a benign effect of the variant on protein function. The variant allele was found at a frequency of 3.6e-05 in 247360 control chromosomes. The available data on variant occurrences in the general population are insufficient to allow any conclusion about variant significance. c.43070T>C has been reported in the literature in at least 1 individual affected with dilated cardiomyopathy (example, Mazzarotto_2020). These report(s) do not provide unequivocal conclusions about association of the variant with TTN-related conditions. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. The following publication has been ascertained in the context of this evaluation (PMID: 31983221). ClinVar contains an entry for this variant (Variation ID: 202686). Based on the evidence outlined above, the variant was classified as uncertain significance. -

Autosomal recessive limb-girdle muscular dystrophy type 2J Uncertain:1

Jan 13, 2018

Illumina Laboratory Services, Illumina

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant was observed in the ICSL laboratory as part of a predisposition screen in an ostensibly healthy population. It had not been previously curated by ICSL or reported in the Human Gene Mutation Database (HGMD: prior to June 1st, 2018), and was therefore a candidate for classification through an automated scoring system. Utilizing variant allele frequency, disease prevalence and penetrance estimates, and inheritance mode, an automated score was calculated to assess if this variant is too frequent to cause the disease. Based on the score, this variant could not be ruled out of causing disease and therefore its association with disease required further investigation. A literature search was performed for the gene, cDNA change, and amino acid change (if applicable). No publications were found based on this search. This variant was therefore classified as a variant of unknown significance for this disease. -

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

Dec 06, 2017

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Dilated cardiomyopathy 1G Uncertain:1

Jan 13, 2018

Illumina Laboratory Services, Illumina

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant was observed in the ICSL laboratory as part of a predisposition screen in an ostensibly healthy population. It had not been previously curated by ICSL or reported in the Human Gene Mutation Database (HGMD: prior to June 1st, 2018), and was therefore a candidate for classification through an automated scoring system. Utilizing variant allele frequency, disease prevalence and penetrance estimates, and inheritance mode, an automated score was calculated to assess if this variant is too frequent to cause the disease. Based on the score, this variant could not be ruled out of causing disease and therefore its association with disease required further investigation. A literature search was performed for the gene, cDNA change, and amino acid change (if applicable). No publications were found based on this search. This variant was therefore classified as a variant of unknown significance for this disease. -

Early-onset myopathy with fatal cardiomyopathy Uncertain:1

Jan 13, 2018

Illumina Laboratory Services, Illumina

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant was observed in the ICSL laboratory as part of a predisposition screen in an ostensibly healthy population. It had not been previously curated by ICSL or reported in the Human Gene Mutation Database (HGMD: prior to June 1st, 2018), and was therefore a candidate for classification through an automated scoring system. Utilizing variant allele frequency, disease prevalence and penetrance estimates, and inheritance mode, an automated score was calculated to assess if this variant is too frequent to cause the disease. Based on the score, this variant could not be ruled out of causing disease and therefore its association with disease required further investigation. A literature search was performed for the gene, cDNA change, and amino acid change (if applicable). No publications were found based on this search. This variant was therefore classified as a variant of unknown significance for this disease. -

Tibial muscular dystrophy Uncertain:1

Jan 13, 2018

Illumina Laboratory Services, Illumina

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant was observed in the ICSL laboratory as part of a predisposition screen in an ostensibly healthy population. It had not been previously curated by ICSL or reported in the Human Gene Mutation Database (HGMD: prior to June 1st, 2018), and was therefore a candidate for classification through an automated scoring system. Utilizing variant allele frequency, disease prevalence and penetrance estimates, and inheritance mode, an automated score was calculated to assess if this variant is too frequent to cause the disease. Based on the score, this variant could not be ruled out of causing disease and therefore its association with disease required further investigation. A literature search was performed for the gene, cDNA change, and amino acid change (if applicable). No publications were found based on this search. This variant was therefore classified as a variant of unknown significance for this disease. -

Myopathy, myofibrillar, 9, with early respiratory failure Uncertain:1

Jan 13, 2018

Illumina Laboratory Services, Illumina

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant was observed in the ICSL laboratory as part of a predisposition screen in an ostensibly healthy population. It had not been previously curated by ICSL or reported in the Human Gene Mutation Database (HGMD: prior to June 1st, 2018), and was therefore a candidate for classification through an automated scoring system. Utilizing variant allele frequency, disease prevalence and penetrance estimates, and inheritance mode, an automated score was calculated to assess if this variant is too frequent to cause the disease. Based on the score, this variant could not be ruled out of causing disease and therefore its association with disease required further investigation. A literature search was performed for the gene, cDNA change, and amino acid change (if applicable). No publications were found based on this search. This variant was therefore classified as a variant of unknown significance for this disease. -

Autosomal recessive limb-girdle muscular dystrophy type 2J;C1838244:Tibial muscular dystrophy;C1858763:Dilated cardiomyopathy 1G;C1861065:Hypertrophic cardiomyopathy 9;C2673677:Early-onset myopathy with fatal cardiomyopathy Uncertain:1

Aug 04, 2021

Department of Pathology and Laboratory Medicine, Sinai Health System

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: research

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Uncertain	0.42
BayesDel_addAF	Benign	-0.14	T
BayesDel_noAF	Benign	-0.25
CADD	Benign	21
DANN	Benign	0.89
Eigen	Uncertain	0.42
Eigen_PC	Uncertain	0.53
FATHMM_MKL	Pathogenic	0.97	D
LIST_S2	Uncertain	0.87	D;T;D;.;T;T;T
M_CAP	Benign	0.016	T
MetaRNN	Benign	0.31	T;T;T;T;T;T;T
MetaSVM	Benign	-0.81	T
MutationAssessor	Uncertain	2.1	.;.;.;M;.;.;M
PhyloP100		7.4
PrimateAI	Uncertain	0.63	T
PROVEAN	Uncertain	-2.6	D;D;.;.;D;D;.
REVEL	Benign	0.23
Sift	Benign	0.31	T;T;.;.;T;T;.
Polyphen		0.78	.;.;.;P;.;.;P
Vest4		0.51
MVP		0.56
MPC		0.20
ClinPred		0.17	T
GERP RS		6.0
Mutation Taster		=87/13	polymorphism

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: rs370067597; hg19: chr2-179476182;