2-178751146-A-T

Variant names:

• chr2-178751146-A-T
• rs144209883
• NM_001267550.2:c.11311+1978T>A

Variant summary

Our verdict is Benign. The variant received -9 ACMG points: 0P and 9B. BP4_Strong BP6 BS1

The NM_001267550.2(TTN):​c.11311+1978T>A variant causes a intron change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000169 in 1,612,716 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).

• Frequency:
  • Genomes: 𝑓 0.00096 (0 hom., cov: 32)
  • Exomes 𝑓: 0.000086 (0 hom.)
• Consequence: TTN NM_001267550.2 intron
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:1 B:5
• Conservation: PhyloP100: 0.217
• Publications: 2 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: Benign. The variant received -9 ACMG points.

• BP4: Computational evidence support a benign effect (MetaRNN=0.0045254827).
• BP6: Variant 2-178751146-A-T is Benign according to our data. Variant chr2-178751146-A-T is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 166277.
• BS1: Variant frequency is greater than expected in population afr. GnomAd4 allele frequency = 0.00096 (146/152078) while in subpopulation AFR AF = 0.00339 (141/41540). AF 95% confidence interval is 0.00294. There are 0 homozygotes in GnomAd4. There are 72 alleles in the male GnomAd4 subpopulation. Median coverage is 32. This position passed quality control check.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_001267550.2. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	TTN	NM_001267550.2	MANE Select	c.11311+1978T>A		intron	N/A	NP_001254479.2
	TTN	NM_133379.5		c.11254T>A	p.Ser3752Thr	missense	Exon 46 of 46	NP_596870.2
	TTN	NM_001256850.1		c.10360+1978T>A		intron	N/A	NP_001243779.1

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	TTN	ENST00000589042.5	TSL:5 MANE Select	c.11311+1978T>A		intron	N/A	ENSP00000467141.1
	TTN	ENST00000446966.2	TSL:1	c.11311+1978T>A		intron	N/A	ENSP00000408004.2
	TTN	ENST00000436599.2	TSL:1	c.11035+1978T>A		intron	N/A	ENSP00000405517.2

Frequencies

GnomAD3 genomes AF: 0.000961 AC: 146 AN: 151960 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.00340

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.000329

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: 0.00

Gnomad OTH AF: 0.00

GnomAD2 exomes AF: 0.000265 AC: 66 AN: 249070 AF XY: 0.000186

Gnomad AFR exome AF: 0.00360

Gnomad AMR exome AF: 0.000233

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.0000863 AC: 126 AN: 1460638 Hom.: 0 Cov.: 73 AF XY: 0.0000729 AC XY: 53 AN XY: 726564

African (AFR) AF: 0.00317 AC: 106 AN: 33440

American (AMR) AF: 0.000202 AC: 9 AN: 44606

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26056

East Asian (EAS) AF: 0.00 AC: 0 AN: 39618

South Asian (SAS) AF: 0.00 AC: 0 AN: 86162

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53292

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5748

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 1111400

Other (OTH) AF: 0.000182 AC: 11 AN: 60316

GnomAD4 genome AF: 0.000960 AC: 146 AN: 152078 Hom.: 0 Cov.: 32 AF XY: 0.000968 AC XY: 72 AN XY: 74348

African (AFR) AF: 0.00339 AC: 141 AN: 41540

American (AMR) AF: 0.000328 AC: 5 AN: 15230

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

East Asian (EAS) AF: 0.00 AC: 0 AN: 5166

South Asian (SAS) AF: 0.00 AC: 0 AN: 4824

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10616

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

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 67916

Other (OTH) AF: 0.00 AC: 0 AN: 2112

Alfa AF: 0.0000298 Hom.: 0

Bravo AF: 0.00105

ESP6500AA AF: 0.00432 AC: 19

ESP6500EA AF: 0.00 AC: 0

ExAC AF: 0.000371 AC: 45

Asia WGS AF: 0.000289 AC: 1 AN: 3478

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:1 Benign:5

Revision: criteria provided, conflicting classifications

Submissions by phenotype

not specified Uncertain:1 Benign:2

Aug 16, 2016

GeneDx

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Missense variants in the TTN gene are considered 'unclassified' if they are not previously reported in the literature and do not have >1% frequency in the population to be considered a polymorphism. Research indicates that truncating mutations in the TTN gene are expected to account for approximately 25% of familial and 18% of sporadic idiopathic DCM; however, truncating variants in the TTN gene have been reported in approximately 3% of reported control alleles. There has been little investigation into non-truncating variants. (Herman D et al. Truncations of titin causing dilated cardiomyopathy. N Eng J Med 366:619-628, 2012) The variant is found in CARDIOMYOPATHY panel(s).

Mar 19, 2012

Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine

Significance: Likely benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Ser3752Thr in exon 45A of TTN: This variant is not expected to have clinical sig nificance because it has been identified in 0.4% (15/3726) of African American c hromosomes from a broad population by the NHLBI Exome Sequencing Project (http:/ /evs.gs.washington.edu/EVS; dbSNP rs144209883). Ser3752Thr in exon 45A of TTN ( rs144209883; allele frequency = 0.4%, 15/3726) **

Apr 09, 2025

Molecular Diagnostic Laboratory for Inherited Cardiovascular Disease, Montreal Heart Institute

Significance: Likely benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

not provided Benign:2

Sep 06, 2023

ARUP Laboratories, Molecular Genetics and Genomics, ARUP Laboratories

Significance: Likely benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Apr 01, 2024

CeGaT Center for Human Genetics Tuebingen

Significance: Likely benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

TTN: BP4

TTN-related disorder Benign:1

Jan 11, 2021

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).

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Benign	-0.63	T
BayesDel_noAF	Benign	-0.68
CADD	Benign	5.1
DANN	Benign	0.51
Eigen	Benign	-1.0
Eigen_PC	Benign	-1.0
FATHMM_MKL	Benign	0.034	N
LIST_S2	Benign	0.28	T
M_CAP	Benign	0.0047	T
MetaRNN	Benign	0.0045	T
MetaSVM	Benign	-1.0	T
PhyloP100		0.22
PROVEAN	Benign	-0.51	N
REVEL	Benign	0.078
Sift	Benign	0.46	T
Sift4G	Benign	0.38	T
Polyphen		0.0060	B
Vest4		0.24
MVP		0.15
ClinPred		0.014	T
GERP RS		1.5
Mutation Taster		=98/2	polymorphism

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

Other links and lift over

dbSNP: rs144209883; hg19: chr2-179615873;