rs140002940

chr2-178635159-A-G

Variant summary

Our verdict is Benign. Variant got -15 ACMG points: 1P and 16B. PP3 BP6_Very_Strong BS1 BS2

The NM_001267550.2(TTN):c.42024+6T>C variant causes a splice donor region, intron change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000981 in 1,610,488 control chromosomes in the GnomAD database, including 17 homozygotes. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Likely benign (★★).

• Frequency:
  • Genomes: 𝑓 0.0049 (5 hom., cov: 32)
  • Exomes 𝑓: 0.00057 (12 hom.)
• Consequence: TTN NM_001267550.2 splice_donor_region, intron
• Scores: Splicing: ADA: 0.9733
• Clinical Significance: Benign/Likely benign criteria provided, multiple submitters, no conflicts B:21
• Conservation: PhyloP100: 3.05

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 -15 ACMG points.

• PP3: Splicing scoreres supports a deletorius effect: Scorers claiming Pathogenic: dbscSNV1_ADA, dbscSNV1_RF. No scorers claiming Uncertain. Scorers claiming Benign: max_spliceai.
• BP6: Variant 2-178635159-A-G is Benign according to our data. Variant chr2-178635159-A-G is described in ClinVar as [Likely_benign]. Clinvar id is 46951.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr2-178635159-A-G is described in Lovd as [Benign]. Variant chr2-178635159-A-G is described in Lovd as [Likely_benign].
• BS1: Variant frequency is greater than expected in population afr. gnomad4 allele frequency = 0.00495 (753/152176) while in subpopulation AFR AF= 0.0165 (684/41546). AF 95% confidence interval is 0.0154. There are 5 homozygotes in gnomad4. There are 380 alleles in male gnomad4 subpopulation. Median coverage is 32. This position pass quality control queck.
• BS2: High Homozygotes in GnomAd at 4 AD,AR gene

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
TTN	NM_001267550.2	c.42024+6T>C		splice_donor_region_variant, intron_variant		ENST00000589042.5

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
TTN	ENST00000589042.5	c.42024+6T>C		splice_donor_region_variant, intron_variant		5	NM_001267550.2	P1
TTN-AS1	ENST00000659121.1	n.502+37478A>G		intron_variant, non_coding_transcript_variant

Frequencies

GnomAD3 genomes AF: 0.00491 AC: 746 AN: 152058 Hom.: 4 Cov.: 32

Gnomad AFR AF: 0.0163

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00262

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00949

Gnomad NFE AF: 0.000206

Gnomad OTH AF: 0.00575

GnomAD3 exomes AF: 0.00125 AC: 308 AN: 245924 Hom.: 1 AF XY: 0.000961 AC XY: 128 AN XY: 133248

Gnomad AFR exome AF: 0.0144

Gnomad AMR exome AF: 0.00157

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad SAS exome AF: 0.000101

Gnomad FIN exome AF: 0.0000465

Gnomad NFE exome AF: 0.000161

Gnomad OTH exome AF: 0.00184

GnomAD4 exome AF: 0.000567 AC: 827 AN: 1458312 Hom.: 12 Cov.: 32 AF XY: 0.000487 AC XY: 353 AN XY: 725270

Gnomad4 AFR exome AF: 0.0167

Gnomad4 AMR exome AF: 0.00187

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.0000469

Gnomad4 FIN exome AF: 0.0000562

Gnomad4 NFE exome AF: 0.0000648

Gnomad4 OTH exome AF: 0.00171

GnomAD4 genome AF: 0.00495 AC: 753 AN: 152176 Hom.: 5 Cov.: 32 AF XY: 0.00511 AC XY: 380 AN XY: 74376

Gnomad4 AFR AF: 0.0165

Gnomad4 AMR AF: 0.00262

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.000206

Gnomad4 OTH AF: 0.00569

Alfa AF: 0.00210 Hom.: 0

Bravo AF: 0.00590

Asia WGS AF: 0.000866 AC: 3 AN: 3478

EpiCase AF: 0.000109

EpiControl AF: 0.000296

ClinVar

Significance: Benign/Likely benign

Submissions summary: Benign:21

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not specified Benign:6

Benign, criteria provided, single submitter	clinical testing	GeneDx	May 01, 2014	This variant is considered likely benign or benign based on one or more of the following criteria: it is a conservative change, it occurs at a poorly conserved position in the protein, it is predicted to be benign by multiple in silico algorithms, and/or has population frequency not consistent with disease. -
Benign, criteria provided, single submitter	clinical testing	Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine	Mar 02, 2012	34320+6T>C in intron 177 of TTN: This variant is not expected to have clinical s ignificance because it has been identified in 1.5% (44/2980) of African American chromosomes from a broad population by the NHLBI Exome Sequencing Project (http ://evs.gs.washington.edu/EVS; dbSNP rs140002940). -
Benign, no assertion criteria provided	clinical testing	Clinical Genetics DNA and cytogenetics Diagnostics Lab, Erasmus MC, Erasmus Medical Center	-	- -
Benign, criteria provided, single submitter	clinical testing	Genetic Services Laboratory, University of Chicago	Aug 14, 2014	- -
Benign, criteria provided, single submitter	clinical testing	Women's Health and Genetics/Laboratory Corporation of America, LabCorp	Oct 30, 2019	Variant summary: TTN c.34320+6T>C alters a conserved nucleotide located close to a canonical splice site and therefore could affect mRNA splicing, leading to a significantly altered protein sequence. Several computational tools predict a significant impact on normal splicing: two predict the variant abolishes a 5' splicing donor site; one predicts the variant weakens a 5' splicing donor site. However, these predictions have yet to be confirmed by functional studies. The variant allele was found at a frequency of 0.0013 in 245924 control chromosomes, predominantly at a frequency of 0.014 within the African or African-American subpopulation in the gnomAD database, including 1 homozygotes. The observed variant frequency within African or African-American control individuals in the gnomAD database is approximately 22 fold of the estimated maximal expected allele frequency for a pathogenic variant in TTN causing Cardiomyopathy phenotype (0.00063), strongly suggesting that the variant is a benign polymorphism found primarily in populations of African or African-American origin. To our knowledge, no occurrence of c.34320+6T>C in individuals affected with Cardiomyopathy and no experimental evidence demonstrating its impact on protein function have been reported. Three clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar after 2014 without evidence for independent evaluation. All laboratories classified the variant as benign. Based on the evidence outlined above, the variant was classified as benign. -
Benign, criteria provided, single submitter	clinical testing	Athena Diagnostics	Apr 21, 2017	- -

not provided Benign:3

Likely benign, no assertion criteria provided	clinical testing	Clinical Genetics, Academic Medical Center	-	- -
Likely benign, no assertion criteria provided	clinical testing	Laboratory of Diagnostic Genome Analysis, Leiden University Medical Center (LUMC)	-	- -
Benign, criteria provided, single submitter	clinical testing	ARUP Laboratories, Molecular Genetics and Genomics, ARUP Laboratories	Feb 08, 2022	- -

Autosomal recessive limb-girdle muscular dystrophy type 2J Benign:2

Benign, criteria provided, single submitter	clinical testing	Genome-Nilou Lab	Sep 10, 2021	- -
Likely benign, criteria provided, single submitter	clinical testing	Illumina Laboratory Services, Illumina	Jan 13, 2018	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 likely benign is not then subjected to further curation. The score for this variant resulted in a classification of likely benign for this disease. -

Early-onset myopathy with fatal cardiomyopathy Benign:2

Likely benign, criteria provided, single submitter	clinical testing	Illumina Laboratory Services, Illumina	Jan 13, 2018	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 likely benign is not then subjected to further curation. The score for this variant resulted in a classification of likely benign for this disease. -
Benign, criteria provided, single submitter	clinical testing	Genome-Nilou Lab	Sep 10, 2021	- -

Tibial muscular dystrophy Benign:2

Benign, criteria provided, single submitter	clinical testing	Illumina Laboratory Services, Illumina	Jan 13, 2018	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. -
Benign, criteria provided, single submitter	clinical testing	Genome-Nilou Lab	Sep 10, 2021	- -

Myopathy, myofibrillar, 9, with early respiratory failure Benign:2

Benign, criteria provided, single submitter	clinical testing	Genome-Nilou Lab	Sep 10, 2021	- -
Benign, criteria provided, single submitter	clinical testing	Illumina Laboratory Services, Illumina	Jan 13, 2018	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. -

TTN-related disorder Benign:1

Benign, criteria provided, single submitter

clinical testing

PreventionGenetics, part of Exact Sciences

May 29, 2019

This variant is classified as 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

Benign, criteria provided, single submitter

clinical testing

Invitae

Jan 31, 2024

- -

Dilated cardiomyopathy 1G Benign:1

Likely benign, criteria provided, single submitter

clinical testing

Illumina Laboratory Services, Illumina

Jan 13, 2018

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 likely benign is not then subjected to further curation. The score for this variant resulted in a classification of likely benign for this disease. -

Cardiomyopathy Benign:1

Benign, criteria provided, single submitter

clinical testing

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

Oct 17, 2017

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.51
Cadd	Uncertain	23
Dann	Benign	0.74

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	0.97
dbscSNV1_RF	Pathogenic	0.87
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

LitVar

Other links and lift over

dbSNP: rs140002940; hg19: chr2-179499886;