chr2-178713381-T-TACAATACAAA

Position:

• chr2-178713381-T-TACAATACAAA

Variant summary

Our verdict is Likely benign. Variant got -1 ACMG points: 0P and 1B. BP6

The NM_001267550.2(TTN):​c.26762-10_26762-9insTTTGTATTGT variant causes a splice polypyrimidine tract, intron change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000364 in 150,898 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).

• Frequency:
  • Genomes: 𝑓 0.00036 (0 hom., cov: 24)
  • Exomes 𝑓: 0.00048 (0 hom.)
  • Failed GnomAD Quality Control
• Consequence: TTN NM_001267550.2 splice_polypyrimidine_tract, intron
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:1 B:4
• Conservation: PhyloP100: 1.08

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 Likely_benign. Variant got -1 ACMG points.

• BP6: Variant 2-178713381-T-TACAATACAAA is Benign according to our data. Variant chr2-178713381-T-TACAATACAAA is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 405188.We mark this variant Likely_benign, oryginal submissions are: {Likely_benign=3, Uncertain_significance=1, Benign=1}.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
TTN	NM_001267550.2	c.26762-10_26762-9insTTTGTATTGT		splice_polypyrimidine_tract_variant, intron_variant		ENST00000589042.5
LOC124906100	XR_007087318.1	n.2186-369_2186-368insTACAAAACAA		intron_variant, non_coding_transcript_variant

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
TTN	ENST00000589042.5	c.26762-10_26762-9insTTTGTATTGT		splice_polypyrimidine_tract_variant, intron_variant		5	NM_001267550.2	P1
TTN-AS1	ENST00000659121.1	n.503-21119_503-21118insTACAAAACAA		intron_variant, non_coding_transcript_variant

Frequencies

GnomAD3 genomes AF: 0.000364 AC: 55 AN: 150898 Hom.: 0 Cov.: 24

Gnomad AFR AF: 0.000342

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.000264

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.0000954

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.000531

Gnomad OTH AF: 0.00

GnomAD4 exome Data not reliable, filtered out with message: AS_VQSR AF: 0.000476 AC: 628 AN: 1318022 Hom.: 0 Cov.: 33 AF XY: 0.000416 AC XY: 267 AN XY: 641890

Gnomad4 AFR exome AF: 0.000105

Gnomad4 AMR exome AF: 0.000136

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.000192

Gnomad4 NFE exome AF: 0.000559

Gnomad4 OTH exome AF: 0.000534

GnomAD4 genome AF: 0.000364 AC: 55 AN: 150898 Hom.: 0 Cov.: 24 AF XY: 0.000313 AC XY: 23 AN XY: 73580

Gnomad4 AFR AF: 0.000342

Gnomad4 AMR AF: 0.000264

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.0000954

Gnomad4 NFE AF: 0.000531

Gnomad4 OTH AF: 0.00

Alfa AF: 0.000337 Hom.: 0

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:1 Benign:4

Revision: criteria provided, conflicting classifications

Submissions by phenotype

not specified Benign:3

Benign, criteria provided, single submitter	clinical testing	Women's Health and Genetics/Laboratory Corporation of America, LabCorp	Aug 14, 2023	Variant summary: TTN c.23030-10_23030-9insTTTGTATTGT results in the insertion of 10 nucleotides at a position not widely known to affect splicing. Several computational tools predict a significant impact on normal splicing: four predict the variant weakens a 3' acceptor site. However, these predictions have yet to be confirmed by functional studies. The variant allele was found at a frequency of 0.00037 in 149680 control chromosomes (i.e., 55 heterozygotes), predominantly at a frequency of 0.00053 within the Non-Finnish European subpopulation in the gnomAD database (v3.1.2). The observed variant frequency within Non-Finnish European control individuals in the gnomAD database is approximately 1.4 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 Non-Finnish European origin. To our knowledge, no occurrence of c.23030-10_23030-9insTTTGTATTGT in individuals affected with Dilated Cardiomyopathy and no experimental evidence demonstrating its impact on protein function have been reported. Four submitters have reported clinical-significance assessments for this variant to ClinVar after 2014; three submitters classified the variant as likely benign, and one submitter classified the variant as uncertain significance. Based on the evidence outlined above, the variant was classified as benign. -
Likely benign, criteria provided, single submitter	clinical testing	Genetic Services Laboratory, University of Chicago	Dec 23, 2016	- -
Likely benign, criteria provided, single submitter	clinical testing	GeneDx	Dec 28, 2017	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. -

not provided Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Eurofins Ntd Llc (ga)

Feb 03, 2017

- -

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

Likely benign, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Jan 29, 2024

- -

Computational scores

Source: dbNSFP v4.3

Splicing

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

LitVar

Other links and lift over

dbSNP: rs1553893826; hg19: chr2-179578108;