2-178532250-C-T

Variant names:

• chr2-178532250-C-T
• rs190565627
• NM_001267550.2:c.104365G>A

Variant summary

Our verdict is Benign. Variant got -9 ACMG points: 0P and 9B. BP4_Strong BP6 BS1

The NM_001267550.2(TTN):​c.104365G>A​(p.Glu34789Lys) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000296 in 1,613,700 control chromosomes in the GnomAD database, including 1 homozygotes. In-silico tool predicts a benign outcome for this variant. 15/19 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).

• Frequency:
  • Genomes: 𝑓 0.0015 (1 hom., cov: 32)
  • Exomes 𝑓: 0.00017 (0 hom.)
• Consequence: TTN NM_001267550.2 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:3 B:12
• Conservation: PhyloP100: 2.00

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 Benign. Variant got -9 ACMG points.

• BP4: Computational evidence support a benign effect (MetaRNN=0.006820619).
• BP6: Variant 2-178532250-C-T is Benign according to our data. Variant chr2-178532250-C-T is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 47669.We mark this variant Likely_benign, oryginal submissions are: {Likely_benign=5, Benign=4, Uncertain_significance=3}. Variant chr2-178532250-C-T is described in Lovd as [Benign].
• BS1: Variant frequency is greater than expected in population afr. gnomad4 allele frequency = 0.00152 (231/152246) while in subpopulation AFR AF= 0.00513 (213/41560). AF 95% confidence interval is 0.00456. There are 1 homozygotes in gnomad4. There are 120 alleles in male gnomad4 subpopulation. Median coverage is 32. This position pass quality control queck.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
TTN	NM_001267550.2	c.104365G>A	p.Glu34789Lys	missense_variant	Exon 358 of 363	ENST00000589042.5	NP_001254479.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
TTN	ENST00000589042.5	c.104365G>A	p.Glu34789Lys	missense_variant	Exon 358 of 363	5	NM_001267550.2	ENSP00000467141.1

Frequencies

GnomAD3 genomes AF: 0.00152 AC: 231 AN: 152128 Hom.: 1 Cov.: 32

Gnomad AFR AF: 0.00514

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.000785

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.000193

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.0000294

Gnomad OTH AF: 0.00144

GnomAD3 exomes AF: 0.000468 AC: 116 AN: 247998 Hom.: 0 AF XY: 0.000342 AC XY: 46 AN XY: 134488

Gnomad AFR exome AF: 0.00601

Gnomad AMR exome AF: 0.000464

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.000223

Gnomad SAS exome AF: 0.0000654

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00000893

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.000169 AC: 247 AN: 1461454 Hom.: 0 Cov.: 40 AF XY: 0.000161 AC XY: 117 AN XY: 727010

Gnomad4 AFR exome AF: 0.00523

Gnomad4 AMR exome AF: 0.000403

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.000101

Gnomad4 SAS exome AF: 0.0000348

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.0000216

Gnomad4 OTH exome AF: 0.000298

GnomAD4 genome AF: 0.00152 AC: 231 AN: 152246 Hom.: 1 Cov.: 32 AF XY: 0.00161 AC XY: 120 AN XY: 74450

Gnomad4 AFR AF: 0.00513

Gnomad4 AMR AF: 0.000784

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.000193

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.0000294

Gnomad4 OTH AF: 0.00142

Alfa AF: 0.000204 Hom.: 0

Bravo AF: 0.00165

ESP6500AA AF: 0.00539 AC: 21

ESP6500EA AF: 0.00 AC: 0

ExAC AF: 0.000505 AC: 61

Asia WGS AF: 0.000289 AC: 1 AN: 3478

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:3 Benign:12

Revision: criteria provided, conflicting classifications

Submissions by phenotype

not specified Benign:4

Jun 10, 2016

Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine

Significance: Likely benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

p.Glu32221Lys in exon 307 of TTN: This variant is not expected to have clinical significance because it has been identified in 0.5% (54/9780) of African chromos omes by the Exome Aggregation Consortium (ExAC, http://exac.broadinstitute.org; dbSNP rs190565627). -

Aug 19, 2016

Eurofins Ntd Llc (ga)

Significance: Likely benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Aug 10, 2020

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

Significance: Benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Variant summary: TTN c.96661G>A (p.Glu32221Lys) results in a conservative amino acid change located in the M-band of the encoded protein sequence. Four of five in-silico tools predict a benign effect of the variant on protein function. The variant allele was found at a frequency of 0.00047 in 247998 control chromosomes, predominantly at a frequency of 0.006 within the African or African-American subpopulation in the gnomAD database. The observed variant frequency within African or African-American control individuals in the gnomAD database is approximately 15 fold of the estimated maximal expected allele frequency for a pathogenic variant in TTN causing Dilated Cardiomyopathy phenotype (0.00039), strongly suggesting that the variant is a benign polymorphism found primarily in populations of African or African-American origin. Seven clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar after 2014 without evidence for independent evaluation (benign/likely benign n=6, VUS n=1). Based on the evidence outlined above, the variant was classified as benign. -

-

Clinical Genetics, Academic Medical Center

Significance: Benign

Review Status: no assertion criteria provided

Collection Method: clinical testing

- -

not provided Benign:3

Apr 01, 2024

CeGaT Center for Human Genetics Tuebingen

Significance: Likely benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

TTN: BS1 -

Sep 28, 2020

GeneDx

Significance: Likely benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant is associated with the following publications: (PMID: 24503780) -

-

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

Significance: Likely benign

Review Status: no assertion criteria provided

Collection Method: clinical testing

- -

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

Jan 12, 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. -

Dilated cardiomyopathy 1G Uncertain:1

Jan 12, 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 12, 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 Benign:1

May 26, 2020

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

Feb 02, 2025

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

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

Jan 12, 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. -

Tibial muscular dystrophy Benign:1

Jan 12, 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. -

Cardiovascular phenotype Benign:1

Oct 17, 2018

Ambry Genetics

Significance: Likely benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This alteration is classified as likely benign based on a combination of the following: seen in unaffected individuals, population frequency, intact protein function, lack of segregation with disease, co-occurrence, RNA analysis, in silico models, amino acid conservation, lack of disease association in case-control studies, and/or the mechanism of disease or impacted region is inconsistent with a known cause of pathogenicity. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.11
BayesDel_addAF	Benign	-0.38	T
BayesDel_noAF	Benign	-0.32
CADD	Benign	18
DANN	Benign	0.88
Eigen	Benign	-0.23
Eigen_PC	Benign	-0.046
FATHMM_MKL	Uncertain	0.88	D
LIST_S2	Uncertain	0.93	D;D;D;.;D;D;D
M_CAP	Benign	0.032	D
MetaRNN	Benign	0.0068	T;T;T;T;T;T;T
MetaSVM	Benign	-0.90	T
MutationAssessor	Benign	0.0	.;.;.;N;.;.;N
PrimateAI	Uncertain	0.53	T
PROVEAN	Benign	-2.3	N;N;.;.;N;N;.
REVEL	Benign	0.17
Sift	Benign	0.053	T;T;.;.;T;T;.
Polyphen		0.010	.;.;.;B;.;.;B
Vest4		0.52
MVP		0.26
MPC		0.094
ClinPred		0.032	T
GERP RS		4.7
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		0.95

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: rs190565627; hg19: chr2-179396977; COSMIC: COSV60169458; COSMIC: COSV60169458;