NM_001267550.2:c.70530G>A

Variant names:

• chr2-178575602-C-T
• rs727503569
• NM_001267550.2:c.70530G>A

Variant summary

Our verdict is Likely benign. The variant received -2 ACMG points: 0P and 2B. BP4_Moderate

The NM_001267550.2(TTN):​c.70530G>A​(p.Met23510Ile) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000372 in 1,613,506 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 15/20 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency:
  • Genomes: 𝑓 0.0000066 (0 hom., cov: 32)
  • Exomes 𝑓: 0.0000034 (0 hom.)
• Consequence: TTN NM_001267550.2 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 1.75
• 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: Likely_benign. The variant received -2 ACMG points.

• BP4: Computational evidence support a benign effect (MetaRNN=0.12795758).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
TTN	NM_001267550.2	c.70530G>A	p.Met23510Ile	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.70530G>A	p.Met23510Ile	missense_variant	Exon 326 of 363	5	NM_001267550.2	ENSP00000467141.1

Frequencies

GnomAD3 genomes AF: 0.00000658 AC: 1 AN: 152088 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

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: 0.0000147

Gnomad OTH AF: 0.00

GnomAD4 exome AF: 0.00000342 AC: 5 AN: 1461418 Hom.: 0 Cov.: 36 AF XY: 0.00000138 AC XY: 1 AN XY: 726988

African (AFR) AF: 0.00 AC: 0 AN: 33462

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

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26128

East Asian (EAS) AF: 0.00 AC: 0 AN: 39676

South Asian (SAS) AF: 0.00 AC: 0 AN: 86246

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53394

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5760

European-Non Finnish (NFE) AF: 0.00000450 AC: 5 AN: 1111666

Other (OTH) AF: 0.00 AC: 0 AN: 60366

GnomAD4 genome AF: 0.00000658 AC: 1 AN: 152088 Hom.: 0 Cov.: 32 AF XY: 0.0000135 AC XY: 1 AN XY: 74272

African (AFR) AF: 0.00 AC: 0 AN: 41450

American (AMR) AF: 0.00 AC: 0 AN: 15264

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 3468

East Asian (EAS) AF: 0.00 AC: 0 AN: 5158

South Asian (SAS) AF: 0.00 AC: 0 AN: 4828

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10618

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 316

European-Non Finnish (NFE) AF: 0.0000147 AC: 1 AN: 67986

Other (OTH) AF: 0.00 AC: 0 AN: 2090

Alfa AF: 0.00 Hom.: 0

Bravo AF: 0.00000378

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

not specified Uncertain:1

Mar 14, 2014

Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The Met20942Ile variant in TTN has not been previously reported in individuals w ith cardiomyopathy and data from large population studies is insufficient to ass ess its frequency. Computational prediction tools and conservation analysis are limited or unavailable for this variant. Additional information is needed to ful ly assess the clinical significance of the Met20942Ile variant -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.58
BayesDel_addAF	Benign	-0.10	T
BayesDel_noAF	Benign	-0.38
CADD	Benign	19
DANN	Benign	0.85
Eigen	Benign	-0.19
Eigen_PC	Benign	0.0042
FATHMM_MKL	Uncertain	0.83	D
LIST_S2	Benign	0.80	T;T;T;.;T;T;T
M_CAP	Benign	0.017	T
MetaRNN	Benign	0.13	T;T;T;T;T;T;T
MetaSVM	Benign	-0.94	T
MutationAssessor	Benign	-0.52	.;.;.;N;.;.;N
PhyloP100		1.8
PrimateAI	Uncertain	0.50	T
PROVEAN	Benign	-2.1	N;N;.;.;N;N;.
REVEL	Benign	0.12
Sift	Benign	0.34	T;T;.;.;T;T;.
Polyphen		0.048	.;.;.;B;.;.;B
Vest4		0.27
MutPred		0.52		.;.;.;Loss of disorder (P = 0.0945);.;.;Loss of disorder (P = 0.0945);
MVP		0.43
MPC		0.11
ClinPred		0.27	T
GERP RS		4.7
Mutation Taster		=31/69	disease causing

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: rs727503569; hg19: chr2-179440329; COSMIC: COSV108175084; COSMIC: COSV108175084;