2-178692043-T-G

Variant names:

• chr2-178692043-T-G
• rs376287951
• NM_001267550.2:c.31735A>C

Variant summary

Our verdict is Likely benign. Variant got -5 ACMG points: 0P and 5B. BP4_Strong BP6

The NM_001267550.2(TTN):​c.31735A>C​(p.Lys10579Gln) variant causes a missense change. The variant allele was found at a frequency of 0.0000415 in 1,613,162 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 0.000059 (0 hom., cov: 32)
  • Exomes 𝑓: 0.000040 (0 hom.)
• Consequence: TTN NM_001267550.2 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:13 B:2
• Conservation: PhyloP100: 6.09

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]

LOC124907912 (HGNC:):

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 -5 ACMG points.

• BP4: Computational evidence support a benign effect (MetaRNN=0.06442559).
• BP6: Variant 2-178692043-T-G is Benign according to our data. Variant chr2-178692043-T-G is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 191996.We mark this variant Likely_benign, oryginal submissions are: {Benign=2, Uncertain_significance=11}.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
TTN	NM_001267550.2	c.31735A>C	p.Lys10579Gln	missense_variant	Exon 121 of 363	ENST00000589042.5	NP_001254479.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
TTN	ENST00000589042.5	c.31735A>C	p.Lys10579Gln	missense_variant	Exon 121 of 363	5	NM_001267550.2	ENSP00000467141.1

Frequencies

GnomAD3 genomes AF: 0.0000657 AC: 10 AN: 152132 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00116

Gnomad SAS AF: 0.000828

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.00

Gnomad OTH AF: 0.00

GnomAD3 exomes AF: 0.0000803 AC: 20 AN: 248950 Hom.: 0 AF XY: 0.0000740 AC XY: 10 AN XY: 135066

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.000780

Gnomad SAS exome AF: 0.000196

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.0000397 AC: 58 AN: 1460912 Hom.: 0 Cov.: 30 AF XY: 0.0000454 AC XY: 33 AN XY: 726714

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.000378

Gnomad4 SAS exome AF: 0.000337

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00000360

Gnomad4 OTH exome AF: 0.000166

GnomAD4 genome AF: 0.0000591 AC: 9 AN: 152250 Hom.: 0 Cov.: 32 AF XY: 0.000107 AC XY: 8 AN XY: 74452

Gnomad4 AFR AF: 0.00

Gnomad4 AMR AF: 0.00

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.000965

Gnomad4 SAS AF: 0.000829

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.00

Gnomad4 OTH AF: 0.00

Alfa AF: 0.0000712 Hom.: 0

Bravo AF: 0.0000302

ExAC AF: 0.0000745 AC: 9

Asia WGS AF: 0.00173 AC: 6 AN: 3478

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:13 Benign:2

Revision: criteria provided, conflicting classifications

Submissions by phenotype

not provided Uncertain:5

Jan 11, 2017

Eurofins Ntd Llc (ga)

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Jun 24, 2013

Biesecker Lab/Clinical Genomics Section, National Institutes of Health

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: research

- -

-

Clinical Genetics DNA and cytogenetics Diagnostics Lab, Erasmus MC, Erasmus Medical Center

Significance: Uncertain significance

Review Status: no assertion criteria provided

Collection Method: clinical testing

- -

May 19, 2023

Revvity Omics, Revvity

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

-

Clinical Genetics, Academic Medical Center

Significance: Uncertain significance

Review Status: no assertion criteria provided

Collection Method: clinical testing

- -

not specified Uncertain:2

Jun 25, 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.Lys9335Gln variant in TTN has not been previously reported in individuals with cardiomyopathy, but has been identified in 7/8600 East Asian chromosomes by the Exome Aggregation Consortium (ExAC, http://exac.broadinstitute.org; dbSNP r s376287951). Computational prediction tools and conservation analysis do not pro vide strong support for or against an impact to the protein. In summary, the cli nical significance of the p.Lys9335Gln variant is uncertain. -

Nov 10, 2023

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.28003A>C (p.Lys9335Gln) results in a conservative amino acid change located in the I-band region of the encoded protein sequence. Three of four in-silico tools predict a benign effect of the variant on protein function. The variant allele was found at a frequency of 8e-05 in 248950 control chromosomes. To our knowledge, no occurrence of c.28003A>C in individuals affected with Limb-Girdle Muscular Dystrophy, Type 2J, or other TTN-related diseases and no experimental evidence demonstrating its impact on protein function have been reported. Five submitters have cited clinical-significance assessments for this variant to ClinVar after 2014 (VUS, n=4; Benign, n=1). Based on the evidence outlined above, the variant was classified as uncertain significance. -

Dilated cardiomyopathy 1G Uncertain:2

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. -

Aug 28, 2019

Victorian Clinical Genetics Services, Murdoch Childrens Research Institute

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

A heterozygous missense variant was identified, NM_001267550.1(TTN):c.31735A>C in exon 121 of 363 of the TTN gene. (NB: This variant is non-coding in NM_003319.4.) This substitution is predicted to create a minor amino acid change from lysine to glutamine at position 10579 of the protein, NP_001254479.1(TTN):p.(Lys10579Gln). The lysine at this position has moderate conservation (100 vertebrates, UCSC), and is located within the PEVK 2 repeat region. In silico software predictions of the pathogenicity of this variant are conflicting (Polyphen, CADD, Mutation Taster). The variant is present in the gnomAD population database at frequencies of 0.09% (17 heterozygotes, 0 homozygotes) and 0.008% (23 heterozygotes, 0 homozygotes) in the East Asian subpopulation and the global population, respectively. It has been previously reported as a VUS in clinical cases (ClinVar, LOVD). Based on information available at the time of curation, this variant has been classified as a VARIANT of UNCERTAIN SIGNIFICANCE (VUS). -

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

Sep 28, 2022

PreventionGenetics, part of Exact Sciences

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The TTN c.31735A>C variant is predicted to result in the amino acid substitution p.Lys10579Gln. To our knowledge, this variant has not been reported in the literature. This variant is reported in 0.087% of alleles in individuals of East Asian descent in gnomAD (http://gnomad.broadinstitute.org/variant/2-179556770-T-G). 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

Apr 20, 2017

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

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 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	Benign	0.25
BayesDel_addAF	Benign	-0.33	T
BayesDel_noAF	Benign	-0.34
CADD	Benign	21
DANN	Uncertain	0.98
DEOGEN2	Benign	0.030	.;.;.;.;T
Eigen	Uncertain	0.31
Eigen_PC	Uncertain	0.39
FATHMM_MKL	Uncertain	0.88	D
LIST_S2	Benign	0.74	T;T;.;T;T
M_CAP	Benign	0.026	D
MetaRNN	Benign	0.064	T;T;T;T;T
MetaSVM	Uncertain	-0.19	T
PrimateAI	Uncertain	0.53	T
PROVEAN	Benign	-2.1	N;.;.;.;D
REVEL	Uncertain	0.30
Sift	Benign	0.088	T;.;.;.;D
Polyphen		0.079	.;.;B;B;.
Vest4		0.32
MutPred		0.44		.;.;Loss of methylation at K10262 (P = 8e-04);Loss of methylation at K10262 (P = 8e-04);.;
MVP		0.38
MPC		0.10
ClinPred		0.066	T
GERP RS		5.4

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: rs376287951; hg19: chr2-179556770;