2-178563493-C-T

Variant names:

• chr2-178563493-C-T
• rs779874042
• NM_001267550.2:c.82639G>A

Variant summary

Our verdict is Likely benign. The variant received -1 ACMG points: 0P and 1B. BP4

The NM_001267550.2(TTN):​c.82639G>A​(p.Glu27547Lys) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.0000103 in 1,461,516 control chromosomes in the GnomAD database, including 1 homozygotes. In-silico tool predicts a benign outcome for this variant. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar. Synonymous variant affecting the same amino acid position (i.e. E27547E) has been classified as Likely benign.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.000010 (1 hom.)
• Consequence: TTN NM_001267550.2 missense
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 7.86
• Publications: 3 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 -1 ACMG points.

• BP4: Computational evidence support a benign effect (MetaRNN=0.34541762).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
TTN	NM_001267550.2	c.82639G>A	p.Glu27547Lys	missense_variant	Exon 326 of 363	ENST00000589042.5	NP_001254479.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
TTN	ENST00000589042.5	c.82639G>A	p.Glu27547Lys	missense_variant	Exon 326 of 363	5	NM_001267550.2	ENSP00000467141.1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD2 exomes AF: 0.0000201 AC: 5 AN: 248666 AF XY: 0.0000222

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 FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.0000103 AC: 15 AN: 1461516 Hom.: 1 Cov.: 37 AF XY: 0.0000138 AC XY: 10 AN XY: 727046

African (AFR) AF: 0.00 AC: 0 AN: 33466

American (AMR) AF: 0.00 AC: 0 AN: 44720

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26130

East Asian (EAS) AF: 0.00 AC: 0 AN: 39666

South Asian (SAS) AF: 0.000174 AC: 15 AN: 86256

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53400

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5766

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 1111752

Other (OTH) AF: 0.00 AC: 0 AN: 60360

GnomAD4 genome Cov.: 33

Alfa AF: 0.00 Hom.: 0

Bravo AF: 0.00000378

ExAC AF: 0.0000331 AC: 4

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.17
BayesDel_addAF	Benign	-0.15	T
BayesDel_noAF	Benign	-0.19
CADD	Benign	22
DANN	Benign	0.96
Eigen	Pathogenic	0.90
Eigen_PC	Pathogenic	0.90
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.97	D;D;D;.;D;D;D
M_CAP	Benign	0.014	T
MetaRNN	Benign	0.35	T;T;T;T;T;T;T
MetaSVM	Benign	-0.36	T
MutationAssessor	Uncertain	2.3	.;.;.;M;.;.;M
PhyloP100		7.9
PrimateAI	Pathogenic	0.81	D
PROVEAN	Uncertain	-3.0	D;D;.;.;D;D;.
REVEL	Uncertain	0.42
Sift	Uncertain	0.012	D;D;.;.;D;D;.
Polyphen		1.0	.;.;.;D;.;.;D
Vest4		0.56
MutPred		0.56		.;.;.;Gain of ubiquitination at E25906 (P = 0.0185);.;.;Gain of ubiquitination at E25906 (P = 0.0185);
MVP		0.33
MPC		0.49
ClinPred		0.30	T
GERP RS		6.0
Mutation Taster		=90/10	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: rs779874042; hg19: chr2-179428220;