2-178679958-CTCTTCT-CTCT

Position:

• chr2-178679958-CTCTTCT-CTCT

Variant summary

Our verdict is Uncertain significance. Variant got 1 ACMG points: 1P and 0B. PM4_Supporting

The NM_001267550.2(TTN):​c.33513_33515del​(p.Glu11172del) variant causes a inframe deletion change. The variant allele was found at a frequency of 0.0000942 in 1,613,002 control chromosomes in the GnomAD database, including 1 homozygotes. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).

• Frequency:
  • Genomes: 𝑓 0.00015 (0 hom., cov: 32)
  • Exomes 𝑓: 0.000088 (1 hom.)
• Consequence: TTN NM_001267550.2 inframe_deletion
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:7 B:1
• Conservation: PhyloP100: 3.88

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]

LOC124906100 (HGNC:):

ACMG classification

Verdict is Uncertain_significance. Variant got 1 ACMG points.

• PM4: Nonframeshift variant in NON repetitive region in NM_001267550.2. Strenght limited to Supporting due to length of the change: 1aa.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
TTN	NM_001267550.2	c.33513_33515del	p.Glu11172del	inframe_deletion	140/363	ENST00000589042.5	NP_001254479.2
LOC124906100	XR_007087318.1	n.2186-33783_2186-33781del		intron_variant, non_coding_transcript_variant

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
TTN	ENST00000589042.5	c.33513_33515del	p.Glu11172del	inframe_deletion	140/363	5	NM_001267550.2	ENSP00000467141	P1
TTN-AS1	ENST00000659121.1	n.503-54533_503-54531del		intron_variant, non_coding_transcript_variant

Frequencies

GnomAD3 genomes AF: 0.000151 AC: 23 AN: 151904 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.000290

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.0000657

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.000386

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00633

Gnomad NFE AF: 0.0000883

Gnomad OTH AF: 0.00

GnomAD3 exomes AF: 0.000125 AC: 31 AN: 248470 Hom.: 0 AF XY: 0.000148 AC XY: 20 AN XY: 134786

Gnomad AFR exome AF: 0.000259

Gnomad AMR exome AF: 0.0000873

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.000223

Gnomad SAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.000169

Gnomad OTH exome AF: 0.000166

GnomAD4 exome AF: 0.0000883 AC: 129 AN: 1460980 Hom.: 1 AF XY: 0.0000936 AC XY: 68 AN XY: 726794

Gnomad4 AFR exome AF: 0.000359

Gnomad4 AMR exome AF: 0.0000896

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.0000756

Gnomad4 SAS exome AF: 0.0000348

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.0000855

Gnomad4 OTH exome AF: 0.000199

GnomAD4 genome AF: 0.000151 AC: 23 AN: 152022 Hom.: 0 Cov.: 32 AF XY: 0.000161 AC XY: 12 AN XY: 74328

Gnomad4 AFR AF: 0.000289

Gnomad4 AMR AF: 0.0000656

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.000387

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.0000884

Gnomad4 OTH AF: 0.00

Bravo AF: 0.000204

EpiCase AF: 0.000164

EpiControl AF: 0.000297

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:7 Benign:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

not provided Uncertain:6 Benign:1

Uncertain significance, criteria provided, single submitter	clinical testing	Eurofins Ntd Llc (ga)	Feb 08, 2017	- -
Uncertain significance, no assertion criteria provided	clinical testing	Laboratory of Diagnostic Genome Analysis, Leiden University Medical Center (LUMC)	-	- -
Uncertain significance, no assertion criteria provided	clinical testing	Clinical Genetics, Academic Medical Center	-	- -
Uncertain significance, criteria provided, single submitter	clinical testing	Revvity Omics, Revvity	Mar 23, 2023	- -
Uncertain significance, criteria provided, single submitter	research	Biesecker Lab/Clinical Genomics Section, National Institutes of Health	Jun 24, 2013	- -
Uncertain significance, criteria provided, single submitter	clinical testing	CeGaT Center for Human Genetics Tuebingen	May 01, 2016	- -
Likely benign, criteria provided, single submitter	clinical testing	GeneDx	Nov 19, 2020	This variant is associated with the following publications: (PMID: 23861362) -

not specified Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

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

Jan 02, 2024

Variant summary: TTN c.29781_29783delAGA (p.Glu9928del) results in an in-frame deletion that is predicted to remove one amino acid from the I-band region of the encoded protein. The variant allele was found at a frequency of 0.00012 in 248470 control chromosomes (gnomAD). This frequency is not significantly higher than estimated for a pathogenic variant in TTN causing Dilated Cardiomyopathy (0.00012 vs 0.00039), allowing no conclusion about variant significance. c.29781_29783delAGA has been reported in the literature in a cohort of individuals with a spectrum of coronary artery disease risk (Ng_2013), however without strong evidence for causality (e.g., lack of clinical and co-segregation data). This report therefore does not provide unequivocal conclusions about association of the variant with Dilated Cardiomyopathy. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. The following publication was ascertained in the context of this evaluation (PMID: 23861362). Four submitters have reported clinical-significance assessments for this variant to ClinVar after 2014 with conflicting interpretations (VUS, n = 3; likely benign, n = 1). Based on the evidence outlined above, the variant was classified as uncertain significance. -

Computational scores

Source: dbNSFP v4.3

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: rs368327166; hg19: chr2-179544685;