2-178611111-A-T

Variant names:

• chr2-178611111-A-T
• rs1163818093
• NM_001267550.2:c.51018T>A

Variant summary

Our verdict is Uncertain significance. The variant received 0 ACMG points: 2P and 2B. PM2 BP4_Moderate

The NM_001267550.2(TTN):​c.51018T>A​(p.Asp17006Glu) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a benign outcome for this variant. 17/20 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★★). Synonymous variant affecting the same amino acid position (i.e. D17006D) has been classified as Likely benign.

• Frequency: Genomes: not found (cov: 32)
• Consequence: TTN NM_001267550.2 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: 0.218
• Publications: 0 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: Uncertain_significance. The variant received 0 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.10679671).

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.51018T>A	p.Asp17006Glu	missense	Exon 270 of 363	NP_001254479.2
	TTN	NM_001256850.1		c.46095T>A	p.Asp15365Glu	missense	Exon 220 of 313	NP_001243779.1
	TTN	NM_133378.4		c.43314T>A	p.Asp14438Glu	missense	Exon 219 of 312	NP_596869.4

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	TTN	ENST00000589042.5	TSL:5 MANE Select	c.51018T>A	p.Asp17006Glu	missense	Exon 270 of 363	ENSP00000467141.1
	TTN	ENST00000446966.2	TSL:1	c.50862T>A	p.Asp16954Glu	missense	Exon 268 of 361	ENSP00000408004.2
	TTN	ENST00000436599.2	TSL:1	c.50742T>A	p.Asp16914Glu	missense	Exon 268 of 361	ENSP00000405517.2

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 33

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not provided Uncertain:2

Oct 09, 2019

Revvity Omics, Revvity

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Nov 11, 2019

ARUP Laboratories, Molecular Genetics and Genomics, ARUP Laboratories

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The TTN c.51018T>A; p.Asp17006Glu variant is rare in the general population (<1% allele frequency in the Genome Aggregation Database) and has not been reported in the medical literature in association with dilated cardiomyopathy (DCM) or other TTN-related disease. The clinical relevance of rare missense variants in this gene, which are identified on average once per individual sequenced in affected populations (Herman 2012), is not well understood. Yet, evidence suggests that the vast majority of such missense variants do not contribute to the clinical outcome of DCM (Begay 2015). Thus, the clinical significance of the p.Asp17006Glu variant cannot be determined with certainty. References: Begay RL et al. Role of Titin Missense Variants in Dilated Cardiomyopathy. J Am Heart Assoc. 2015 Nov 13;4(11). Herman DS et al. Truncations of titin causing dilated cardiomyopathy. N Engl J Med. 2012 Feb 16;366(7):619-28. Linke and Hamdani. Gigantic business: titin properties and function through thick and thin. Circ Res 2014; 114(6): 1052-1068.

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.21
BayesDel_addAF	Benign	-0.16	T
BayesDel_noAF	Benign	-0.46
CADD	Benign	15
DANN	Benign	0.81
Eigen	Benign	-0.52
Eigen_PC	Benign	-0.38
FATHMM_MKL	Uncertain	0.90	D
LIST_S2	Benign	0.68	T
M_CAP	Benign	0.012	T
MetaRNN	Benign	0.11	T
MetaSVM	Benign	-1.0	T
MutationAssessor	Benign	0.035	N
PhyloP100		0.22
PrimateAI	Benign	0.43	T
PROVEAN	Benign	-1.9	N
REVEL	Benign	0.083
Sift	Benign	0.69	T
Polyphen		0.0060	B
Vest4		0.42
MutPred		0.54		Gain of disorder (P = 0.1336)
MVP		0.10
MPC		0.082
ClinPred		0.036	T
GERP RS		-0.47
Mutation Taster		=74/26	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: rs1163818093; hg19: chr2-179475838;