2-178792086-C-T

Variant names:

• chr2-178792086-C-T
• rs759126894
• NM_001267550.2:c.1648G>A

Variant summary

Our verdict is Likely benign. Variant got -2 ACMG points: 2P and 4B. PM2 BP4_Strong

The NM_001267550.2(TTN):​c.1648G>A​(p.Val550Ile) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000274 in 1,460,170 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 14/18 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0000027 (0 hom.)
• Consequence: TTN NM_001267550.2 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: -0.0170

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]

ACMG classification

Verdict is Likely_benign. Variant got -2 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.044585228).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
TTN	NM_001267550.2	c.1648G>A	p.Val550Ile	missense_variant	Exon 10 of 363	ENST00000589042.5	NP_001254479.2
TTN	NM_133379.5	c.1648G>A	p.Val550Ile	missense_variant	Exon 10 of 46	ENST00000360870.10	NP_596870.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
TTN	ENST00000589042.5	c.1648G>A	p.Val550Ile	missense_variant	Exon 10 of 363	5	NM_001267550.2	ENSP00000467141.1
TTN	ENST00000360870.10	c.1648G>A	p.Val550Ile	missense_variant	Exon 10 of 46	5	NM_133379.5	ENSP00000354117.4

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD3 exomes AF: 0.00000800 AC: 2 AN: 249878 Hom.: 0 AF XY: 0.00000740 AC XY: 1 AN XY: 135078

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: 0.0000657

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000274 AC: 4 AN: 1460170 Hom.: 0 Cov.: 31 AF XY: 0.00000275 AC XY: 2 AN XY: 726384

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.0000224

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.0000349

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 33

Bravo AF: 0.00000756

Asia WGS AF: 0.000289 AC: 1 AN: 3476

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

not provided Uncertain:1

Dec 14, 2022

Revvity Omics, Revvity

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.068
BayesDel_addAF	Benign	-0.37	T
BayesDel_noAF	Benign	-0.59
CADD	Benign	15
DANN	Benign	0.92
Eigen	Benign	-0.55
Eigen_PC	Benign	-0.38
FATHMM_MKL	Benign	0.19	N
LIST_S2	Benign	0.74	T;T;T;.;T;T;T;T;T
M_CAP	Benign	0.0071	T
MetaRNN	Benign	0.045	T;T;T;T;T;T;T;T;T
MetaSVM	Benign	-1.0	T
PrimateAI	Benign	0.31	T
PROVEAN	Benign	-0.040	N;N;.;.;N;N;.;N;N
REVEL	Benign	0.11
Sift	Benign	0.71	T;T;.;.;T;T;.;T;T
Sift4G	Benign	0.43	.;.;.;.;.;.;.;T;.
Polyphen		0.0, 0.0010	.;.;.;B;.;.;B;B;.
Vest4		0.073
MutPred		0.32		Loss of helix (P = 0.0033);Loss of helix (P = 0.0033);Loss of helix (P = 0.0033);Loss of helix (P = 0.0033);Loss of helix (P = 0.0033);Loss of helix (P = 0.0033);Loss of helix (P = 0.0033);Loss of helix (P = 0.0033);.;
MVP		0.18
MPC		0.068
ClinPred		0.068	T
GERP RS		-0.31

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: rs759126894; hg19: chr2-179656813;