rs199565715

Variant names:

• chr2-178756220-A-G
• rs199565715
• NM_001267550.2:c.11254+2T>C

Variant summary

Our verdict is Likely benign. The variant received -3 ACMG points: 2P and 5B. PVS1_Moderate BP6 BS1

The NM_001267550.2(TTN):​c.11254+2T>C variant causes a splice donor, intron change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000248 in 1,589,862 control chromosomes in the GnomAD database, including 1 homozygotes. In-silico tool predicts a benign outcome for this variant. 2/2 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 (1 hom., cov: 33)
  • Exomes 𝑓: 0.00013 (0 hom.)
• Consequence: TTN NM_001267550.2 splice_donor, intron
• Scores: Splicing: ADA: 0.8959
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:1 B:7
• Conservation: PhyloP100: 0.806
• Publications: 4 publications found

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

Our verdict: Likely_benign. The variant received -3 ACMG points.

• PVS1: Splicing +-2 bp (donor or acceptor) variant, product NOT destroyed by NMD, known LOF gene, truncates exone, which is 0.005334519 fraction of the gene. No cryptic splice site detected. Exon removal is inframe change.
• BP6: Variant 2-178756220-A-G is Benign according to our data. Variant chr2-178756220-A-G is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 178264.
• BS1: Variant frequency is greater than expected in population afr. GnomAd4 allele frequency = 0.00133 (203/152304) while in subpopulation AFR AF = 0.00474 (197/41584). AF 95% confidence interval is 0.0042. There are 1 homozygotes in GnomAd4. There are 106 alleles in the male GnomAd4 subpopulation. Median coverage is 33. This position passed quality control check.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
TTN	NM_001267550.2	c.11254+2T>C		splice_donor_variant, intron_variant	Intron 46 of 362	ENST00000589042.5	NP_001254479.2
TTN	NM_133379.5	c.10303+2764T>C		intron_variant	Intron 44 of 45	ENST00000360870.10	NP_596870.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
TTN	ENST00000589042.5	c.11254+2T>C		splice_donor_variant, intron_variant	Intron 46 of 362	5	NM_001267550.2	ENSP00000467141.1
TTN	ENST00000360870.10	c.10303+2764T>C		intron_variant	Intron 44 of 45	5	NM_133379.5	ENSP00000354117.4

Frequencies

GnomAD3 genomes AF: 0.00133 AC: 203 AN: 152186 Hom.: 1 Cov.: 33

Gnomad AFR AF: 0.00475

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.000196

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.0000441

Gnomad OTH AF: 0.00

GnomAD2 exomes AF: 0.000303 AC: 73 AN: 240574 AF XY: 0.000269

Gnomad AFR exome AF: 0.00415

Gnomad AMR exome AF: 0.000119

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.0000183

Gnomad OTH exome AF: 0.000172

GnomAD4 exome AF: 0.000134 AC: 192 AN: 1437558 Hom.: 0 Cov.: 26 AF XY: 0.000117 AC XY: 83 AN XY: 711768

African (AFR) AF: 0.00484 AC: 159 AN: 32884

American (AMR) AF: 0.000138 AC: 6 AN: 43596

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 25378

East Asian (EAS) AF: 0.00 AC: 0 AN: 39280

South Asian (SAS) AF: 0.0000476 AC: 4 AN: 84096

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 51744

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5662

European-Non Finnish (NFE) AF: 9.13e-7 AC: 1 AN: 1095598

Other (OTH) AF: 0.000371 AC: 22 AN: 59320

GnomAD4 genome AF: 0.00133 AC: 203 AN: 152304 Hom.: 1 Cov.: 33 AF XY: 0.00142 AC XY: 106 AN XY: 74468

African (AFR) AF: 0.00474 AC: 197 AN: 41584

American (AMR) AF: 0.000196 AC: 3 AN: 15288

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 3470

East Asian (EAS) AF: 0.00 AC: 0 AN: 5176

South Asian (SAS) AF: 0.00 AC: 0 AN: 4816

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10624

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 294

European-Non Finnish (NFE) AF: 0.0000441 AC: 3 AN: 68024

Other (OTH) AF: 0.00 AC: 0 AN: 2116

Alfa AF: 0.000361 Hom.: 4

Bravo AF: 0.00138

ESP6500AA AF: 0.00438 AC: 17

ESP6500EA AF: 0.00 AC: 0

ExAC AF: 0.000381 AC: 46

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:1 Benign:7

Revision: criteria provided, conflicting classifications

Submissions by phenotype

not specified Uncertain:1 Benign:3

Jan 27, 2017

Eurofins Ntd Llc (ga)

Significance: Likely benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

May 28, 2014

Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Variant classified as Uncertain Significance - Favor Benign. The 10741+2T>C vari ant in TTN has not been previously reported in individuals with cardiomyopathy, but has been identified in 0.4% (17/3882) of African American chromosomes by the NHLBI Exome Sequencing Project (http://evs.gs.washington.edu/EVS/; dbSNP rs1995 65715). This variant occurs in the invariant region (+/- 1,2) of the splice cons ensus sequence. Splice and other truncating variants in TTN are strongly associa ted with DCM, particularly if they are located in exons encoding for the A-band region of the protein (Herman 2012, Pugh 2014). Variants in the I-band (where th e 10741+2T>C variant is located) occur at greater frequency in controls than in patients (Pugh 2014). This decreases but does not rule out that this variant ha s a role in disease. In summary, while the clinical significance of the 10741+2T >C variant is uncertain, these data suggest that it is more likely to be benign. -

Mar 08, 2023

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.10303+2764T>C is located at a position not widely known to affect splicing. 4/4 computational tools predict no significant impact on normal splicing. However, these predictions have yet to be confirmed by functional studies. In a different transcript this variant has also been reported as a splice site variant (i.e. NM_001267550, c.11254+2T>C), however, the PSI value (proportion spliced-in) for the neighboring exon is very low (see e.g. in McAfee_2021), therefore it's significance is unclear. The variant allele was found at a frequency of 0.0013 in 150958 control chromosomes, predominantly at a frequency of 0.0048 within the African or African-American subpopulation in the gnomAD database, including 1 homozygote. The observed variant frequency within African or African-American control individuals in the gnomAD database is approximately 12 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. The variant, c.10303+2764T>C, has been reported in the literature in individuals affected with cardiomyopathy, however without evidence for causality (Ware_2016, McAfee_2021). These reports do 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. Five clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar after 2014 without evidence for independent evaluation and classified as VUS (n=1), Likely benign (n=3) or Benign (n=1). Based on the evidence outlined above, the variant was classified as benign. -

Nov 07, 2019

Athena Diagnostics

Significance: Benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

not provided Benign:2

Sep 01, 2024

CeGaT Center for Human Genetics Tuebingen

Significance: Likely benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

TTN: BS1 -

Jul 08, 2020

GeneDx

Significance: Likely benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant is associated with the following publications: (PMID: 26735901) -

TTN-related disorder Benign:1

Jul 07, 2022

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 29, 2025

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Likely benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Benign	-0.16	T
BayesDel_noAF	Uncertain	-0.010
CADD	Benign	18
DANN	Benign	0.83
Eigen	Uncertain	0.63
Eigen_PC	Uncertain	0.40
FATHMM_MKL	Uncertain	0.85	D
PhyloP100		0.81
GERP RS		0.78
Mutation Taster		=8/92	disease causing

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Benign	0.90
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

Other links and lift over

dbSNP: rs199565715; hg19: chr2-179620947;