NM_001267550.2:c.55952A>G

Variant names:

• chr2-178600952-T-C
• rs876658067
• NM_001267550.2:c.55952A>G

Variant summary

Our verdict is Likely benign. Variant got -1 ACMG points: 0P and 1B. BP4

The NM_001267550.2(TTN):​c.55952A>G​(p.Glu18651Gly) variant causes a missense change. The variant allele was found at a frequency of 0.00000821 in 1,460,920 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 13/19 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000082 (0 hom.)
• Consequence: TTN NM_001267550.2 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 6.11

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 Likely_benign. Variant got -1 ACMG points.

• BP4: Computational evidence support a benign effect (MetaRNN=0.37064406).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
TTN	NM_001267550.2	c.55952A>G	p.Glu18651Gly	missense_variant	Exon 288 of 363	ENST00000589042.5	NP_001254479.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
TTN	ENST00000589042.5	c.55952A>G	p.Glu18651Gly	missense_variant	Exon 288 of 363	5	NM_001267550.2	ENSP00000467141.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD3 exomes AF: 0.00000403 AC: 1 AN: 248074 Hom.: 0 AF XY: 0.00000744 AC XY: 1 AN XY: 134468

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad SAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00000893

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000821 AC: 12 AN: 1460920 Hom.: 0 Cov.: 32 AF XY: 0.0000124 AC XY: 9 AN XY: 726758

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00000720

Gnomad4 OTH exome AF: 0.0000663

GnomAD4 genome Cov.: 32

Alfa AF: 0.0000312 Hom.: 0

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

not specified Uncertain:1

Mar 11, 2015

Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The p.Glu16083Gly variant in TTN has not been previously reported in individuals with cardiomyopathy or in large population studies. Computational prediction t ools and conservation analysis do not provide strong support for or against an i mpact to the protein. In summary, the clinical significance of the p.Glu16083Gly variant is uncertain. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.24
BayesDel_addAF	Benign	-0.012	T
BayesDel_noAF	Benign	-0.26
CADD	Benign	22
DANN	Benign	0.91
Eigen	Benign	0.14
Eigen_PC	Uncertain	0.24
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Benign	0.79	T;T;T;.;T;T;T
M_CAP	Benign	0.051	D
MetaRNN	Benign	0.37	T;T;T;T;T;T;T
MetaSVM	Benign	-0.63	T
MutationAssessor	Uncertain	2.5	.;.;.;M;.;.;M
PrimateAI	Benign	0.41	T
PROVEAN	Pathogenic	-5.0	D;D;.;.;D;D;.
REVEL	Benign	0.27
Sift	Benign	0.041	D;D;.;.;D;D;.
Polyphen		0.014	.;.;.;B;.;.;B
Vest4		0.57
MutPred		0.63		.;.;.;Loss of loop (P = 0.1242);.;.;Loss of loop (P = 0.1242);
MVP		0.33
MPC		0.10
ClinPred		0.31	T
GERP RS		4.5

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

Publications

LitVar

Other links and lift over

dbSNP: rs876658067; hg19: chr2-179465679;