NM_001267550.2:c.16621+7A>T

Variant names:

• chr2-178732433-T-A
• rs10200398
• NM_001267550.2:c.16621+7A>T

Variant summary

Our verdict is Benign. Variant got -13 ACMG points: 0P and 13B. BP4_Strong BP6 BS1 BS2

The NM_001267550.2(TTN):​c.16621+7A>T variant causes a splice region, intron change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000478 in 1,595,782 control chromosomes in the GnomAD database, including 2 homozygotes. In-silico tool predicts a benign outcome for this variant. 3/3 splice prediction tools predict no significant impact on normal splicing. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).

• Frequency:
  • Genomes: 𝑓 0.0013 (0 hom., cov: 33)
  • Exomes 𝑓: 0.00039 (2 hom.)
• Consequence: TTN NM_001267550.2 splice_region, intron
• Scores: Splicing: ADA: 0.00001201
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:2 B:15
• 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]

ACMG classification

Verdict is Benign. Variant got -13 ACMG points.

• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.81).
• BP6: Variant 2-178732433-T-A is Benign according to our data. Variant chr2-178732433-T-A is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 46619.We mark this variant Likely_benign, oryginal submissions are: {Likely_benign=1, Benign=9, Uncertain_significance=2}. Variant chr2-178732433-T-A is described in Lovd as [Benign]. Variant chr2-178732433-T-A is described in Lovd as [Likely_benign].
• BS1: Variant frequency is greater than expected in population afr. gnomad4 allele frequency = 0.00131 (199/152286) while in subpopulation AFR AF= 0.00383 (159/41562). AF 95% confidence interval is 0.00334. There are 0 homozygotes in gnomad4. There are 103 alleles in male gnomad4 subpopulation. Median coverage is 33. This position pass quality control queck.
• BS2: High Homozygotes in GnomAdExome4 at 2 AD,AR gene

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
TTN	NM_001267550.2	c.16621+7A>T		splice_region_variant, intron_variant	Intron 56 of 362	ENST00000589042.5	NP_001254479.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
TTN	ENST00000589042.5	c.16621+7A>T		splice_region_variant, intron_variant	Intron 56 of 362	5	NM_001267550.2	ENSP00000467141.1

Frequencies

GnomAD3 genomes AF: 0.00131 AC: 200 AN: 152168 Hom.: 0 Cov.: 33

Gnomad AFR AF: 0.00386

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.000655

Gnomad ASJ AF: 0.00144

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.0253

Gnomad NFE AF: 0.000220

Gnomad OTH AF: 0.000957

GnomAD3 exomes AF: 0.000708 AC: 169 AN: 238564 Hom.: 0 AF XY: 0.000658 AC XY: 85 AN XY: 129250

Gnomad AFR exome AF: 0.00419

Gnomad AMR exome AF: 0.000885

Gnomad ASJ exome AF: 0.00337

Gnomad EAS exome AF: 0.00

Gnomad SAS exome AF: 0.0000719

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.000357

Gnomad OTH exome AF: 0.000702

GnomAD4 exome AF: 0.000391 AC: 564 AN: 1443496 Hom.: 2 Cov.: 36 AF XY: 0.000358 AC XY: 256 AN XY: 715772

Gnomad4 AFR exome AF: 0.00491

Gnomad4 AMR exome AF: 0.000937

Gnomad4 ASJ exome AF: 0.00328

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.0000239

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.000204

Gnomad4 OTH exome AF: 0.000639

GnomAD4 genome AF: 0.00131 AC: 199 AN: 152286 Hom.: 0 Cov.: 33 AF XY: 0.00138 AC XY: 103 AN XY: 74454

Gnomad4 AFR AF: 0.00383

Gnomad4 AMR AF: 0.000654

Gnomad4 ASJ AF: 0.00144

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.000221

Gnomad4 OTH AF: 0.000947

Alfa AF: 0.00101 Hom.: 0

Bravo AF: 0.00149

Asia WGS AF: 0.00115 AC: 4 AN: 3476

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:2 Benign:15

Revision: criteria provided, conflicting classifications

Submissions by phenotype

not specified Benign:6

Jun 06, 2017

Athena Diagnostics

Significance: Benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Mar 14, 2012

Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine

Significance: Benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

12889+7A>T in intron 53 of TTN: This variant is not expected to have clinical si gnificance because it is not located within the splice consensus sequence and ha s been identified in 0.4% (13/3156) of African American chromosomes from a broad population by the NHLBI Exome Sequencing Project (http://evs.gs.washington.edu/ EVS; dbSNP rs10200398). -

Sep 04, 2014

GeneDx

Significance: Benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

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. -

Feb 22, 2016

Eurofins Ntd Llc (ga)

Significance: Benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

-

Clinical Genetics, Academic Medical Center

Significance: Benign

Review Status: no assertion criteria provided

Collection Method: clinical testing

- -

Mar 25, 2021

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.12889+7A>T alters a non-conserved nucleotide located close to a canonical splice site and therefore could affect mRNA splicing, leading to a significantly altered protein sequence. 2/3 computational tools predict no significant impact on normal splicing, while one predicts the variant abolishes 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 0.00071 in 238564 control chromosomes, predominantly at a frequency of 0.0042 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 10-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. To our knowledge, no occurrence of c.12889+7A>T in individuals affected with Dilated Cardiomyopathy and no experimental evidence demonstrating its impact on protein function have been reported. Five clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar after 2014 without evidence for independent evaluation, and all of them classified the variant as benign (n=4) / likely benign (n=1). Based on the evidence outlined above, the variant was classified as benign. -

not provided Benign:4

Feb 01, 2025

CeGaT Center for Human Genetics Tuebingen

Significance: Likely benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

TTN: BP4, BS1 -

-

Laboratory of Diagnostic Genome Analysis, Leiden University Medical Center (LUMC)

Significance: Likely benign

Review Status: no assertion criteria provided

Collection Method: clinical testing

- -

-

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

- -

-

Diagnostic Laboratory, Department of Genetics, University Medical Center Groningen

Significance: Likely benign

Review Status: no assertion criteria provided

Collection Method: clinical testing

- -

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

Apr 27, 2017

Illumina Laboratory Services, Illumina

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant was observed as part of a predisposition screen in an ostensibly healthy population. A literature search was performed for the gene, cDNA change, and amino acid change (where applicable). No publications were found based on this search. Allele frequency data from public databases did not allow this variant to be ruled in or out of causing disease. Therefore, this variant is classified as a variant of unknown significance. -

Early-onset myopathy with fatal cardiomyopathy Uncertain:1

Apr 27, 2017

Illumina Laboratory Services, Illumina

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant was observed as part of a predisposition screen in an ostensibly healthy population. A literature search was performed for the gene, cDNA change, and amino acid change (where applicable). No publications were found based on this search. Allele frequency data from public databases did not allow this variant to be ruled in or out of causing disease. Therefore, this variant is classified as a variant of unknown significance. -

TTN-related disorder Benign:1

Aug 03, 2019

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

Jan 27, 2025

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Dilated cardiomyopathy 1G Benign:1

Apr 27, 2017

Illumina Laboratory Services, Illumina

Significance: Benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant was observed as part of a predisposition screen in an ostensibly healthy population. A literature search was performed for the gene, cDNA change, and amino acid change (where applicable). No publications were found based on this search. Allele frequency data from public databases was too high to be consistent with this variant causing disease. Therefore, this variant is classified as benign. -

Tibial muscular dystrophy Benign:1

Apr 27, 2017

Illumina Laboratory Services, Illumina

Significance: Benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant was observed as part of a predisposition screen in an ostensibly healthy population. A literature search was performed for the gene, cDNA change, and amino acid change (where applicable). No publications were found based on this search. Allele frequency data from public databases was too high to be consistent with this variant causing disease. Therefore, this variant is classified as benign. -

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

Apr 27, 2017

Illumina Laboratory Services, Illumina

Significance: Benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant was observed as part of a predisposition screen in an ostensibly healthy population. A literature search was performed for the gene, cDNA change, and amino acid change (where applicable). No publications were found based on this search. Allele frequency data from public databases was too high to be consistent with this variant causing disease. Therefore, this variant is classified as benign. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.81
CADD	Benign	0.16
DANN	Benign	0.74

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Benign	0.000012
dbscSNV1_RF	Benign	0.026
SpliceAI score (max)		0.020		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: rs10200398; hg19: chr2-179597160;