rs199796249

Variant names:

• chr2-178728277-T-A
• rs199796249
• NM_001267550.2:c.19547A>T

Variant summary

Our verdict is Likely benign. Variant got -2 ACMG points: 0P and 2B. BP4 BP6

The NM_001267550.2(TTN):​c.19547A>T​(p.Lys6516Met) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.000369 in 1,613,184 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).

• Frequency:
  • Genomes: 𝑓 0.00025 (0 hom., cov: 33)
  • Exomes 𝑓: 0.00038 (0 hom.)
• Consequence: TTN NM_001267550.2 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:10 B:5
• Conservation: PhyloP100: 7.97

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

Verdict is Likely_benign. Variant got -2 ACMG points.

• BP4: Computational evidence support a benign effect (MetaRNN=0.39737353).
• BP6: Variant 2-178728277-T-A is Benign according to our data. Variant chr2-178728277-T-A is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 192021.We mark this variant Likely_benign, oryginal submissions are: {Likely_benign=3, Benign=2, Uncertain_significance=10}.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
TTN	NM_001267550.2	c.19547A>T	p.Lys6516Met	missense_variant	Exon 67 of 363	ENST00000589042.5	NP_001254479.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
TTN	ENST00000589042.5	c.19547A>T	p.Lys6516Met	missense_variant	Exon 67 of 363	5	NM_001267550.2	ENSP00000467141.1

Frequencies

GnomAD3 genomes AF: 0.000250 AC: 38 AN: 152128 Hom.: 0 Cov.: 33

Gnomad AFR AF: 0.0000241

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: 0.000544

Gnomad OTH AF: 0.00

GnomAD3 exomes AF: 0.000149 AC: 37 AN: 247900 Hom.: 0 AF XY: 0.000119 AC XY: 16 AN XY: 134470

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.0000291

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad SAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.000304

Gnomad OTH exome AF: 0.000333

GnomAD4 exome AF: 0.000382 AC: 558 AN: 1461056 Hom.: 0 Cov.: 32 AF XY: 0.000358 AC XY: 260 AN XY: 726766

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: 0.000454

Gnomad4 OTH exome AF: 0.000879

GnomAD4 genome AF: 0.000250 AC: 38 AN: 152128 Hom.: 0 Cov.: 33 AF XY: 0.000215 AC XY: 16 AN XY: 74308

Gnomad4 AFR AF: 0.0000241

Gnomad4 AMR AF: 0.00

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.000544

Gnomad4 OTH AF: 0.00

Alfa AF: 0.000463 Hom.: 0

Bravo AF: 0.000253

TwinsUK AF: 0.000270 AC: 1

ALSPAC AF: 0.000259 AC: 1

ESP6500AA AF: 0.00 AC: 0

ESP6500EA AF: 0.000977 AC: 8

ExAC AF: 0.000124 AC: 15

EpiCase AF: 0.000437

EpiControl AF: 0.000237

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:10 Benign:5

Revision: criteria provided, conflicting classifications

Submissions by phenotype

not provided Uncertain:5 Benign:2

Jul 26, 2021

Mayo Clinic Laboratories, Mayo Clinic

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Nov 29, 2016

Eurofins Ntd Llc (ga)

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Dec 26, 2023

Revvity Omics, Revvity

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Oct 15, 2020

GeneDx

Significance: Likely benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Mar 17, 2022

ARUP Laboratories, Molecular Genetics and Genomics, ARUP Laboratories

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The TTN c.15815A>T; p.Lys5272Met variant (rs199796249; ClinVar Variation ID: 192021) is rare in the general population (<1% allele frequency in the Genome Aggregation Database) and has not been reported in the medical literature in association with dilated cardiomyopathy (DCM) or other TTN-related disease. The clinical relevance of rare missense variants in this gene, which are identified on average once per individual sequenced in affected populations (Herman 2012), is not well understood. Yet, evidence suggests that the vast majority of such missense variants do not contribute to the clinical outcome of DCM (Begay 2015). Thus, the clinical significance of the p.Lys5272Met variant cannot be determined with certainty. -

Nov 01, 2023

CeGaT Center for Human Genetics Tuebingen

Significance: Likely benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

TTN: BP4 -

Jun 24, 2013

Biesecker Lab/Clinical Genomics Section, National Institutes of Health

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: research

- -

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. -

TTN-related disorder Uncertain:1

Nov 23, 2022

PreventionGenetics, part of Exact Sciences

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The TTN c.19547A>T variant is predicted to result in the amino acid substitution p.Lys6516Met. This variant was reported as a variant of uncertain significance in an unselected exome cohort being analyzed to identify highly penetrant secondary arrhythmia and cardiomyopathy-associated gene variants (described in Supplementary Table 3 as c.15815A>T, p.Lys5272Met based on transcript NM_133378.4 in Ng et al. 2013. PubMed ID: 23861362). This variant is reported in 0.031% of alleles in individuals of European (Non-Finnish) descent in gnomAD (http://gnomad.broadinstitute.org/variant/2-179593004-T-A). At this time, the clinical significance of this variant is uncertain due to the absence of conclusive functional and genetic evidence. -

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

Oct 05, 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. -

Cardiomyopathy Benign:1

Dec 01, 2022

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

Significance: Likely benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Tibial muscular dystrophy Benign:1

Jan 13, 2018

Illumina Laboratory Services, Illumina

Significance: Benign

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 and internal cut-off values, a variant classified as benign is not then subjected to further curation. The score for this variant resulted in a classification of benign for this disease. -

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

Jan 13, 2018

Illumina Laboratory Services, Illumina

Significance: Benign

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 and internal cut-off values, a variant classified as benign is not then subjected to further curation. The score for this variant resulted in a classification of benign for this disease. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.78
BayesDel_addAF	Benign	-0.21	T
BayesDel_noAF	Benign	-0.23
CADD	Benign	23
DANN	Benign	0.91
Eigen	Pathogenic	0.94
Eigen_PC	Pathogenic	0.89
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Benign	0.78	T;T;.;T
M_CAP	Benign	0.044	D
MetaRNN	Benign	0.40	T;T;T;T
MetaSVM	Uncertain	0.073	D
PrimateAI	Benign	0.45	T
PROVEAN	Uncertain	-4.0	D;.;.;.
REVEL	Uncertain	0.55
Sift	Uncertain	0.0070	D;.;.;.
Polyphen		1.0	.;.;D;D
Vest4		0.48
MVP		0.55
MPC		0.53
ClinPred		0.11	T
GERP RS		5.8

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: rs199796249; hg19: chr2-179593004; COSMIC: COSV104641065; COSMIC: COSV104641065;