rs727505068

Positions:

• chr2-178790817-G-A

Variant summary

Our verdict is Likely benign. Variant got -1 ACMG points: 3P and 4B. PM2 PP2 BP4_Strong

The NM_001267550.2(TTN):​c.1691C>T​(p.Ala564Val) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000000684 in 1,461,796 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: 32)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: TTN NM_001267550.2 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 0.388

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 -1 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP2: Missense variant in gene, where missense usually causes diseases (based on misZ statistic), TTN. . Gene score misZ -1.1021 (greater than the threshold 3.09). Trascript score misZ 6.9794 (greater than threshold 3.09). GenCC has associacion of gene with dilated cardiomyopathy, tibial muscular dystrophy, early-onset myopathy with fatal cardiomyopathy, autosomal recessive centronuclear myopathy, hypertrophic cardiomyopathy, hypertrophic cardiomyopathy 9, TTN-related myopathy, dilated cardiomyopathy 1G, arrhythmogenic right ventricular cardiomyopathy, myopathy, myofibrillar, 9, with early respiratory failure, familial isolated dilated cardiomyopathy, childhood-onset progressive contractures-limb-girdle weakness-muscle dystrophy syndrome, autosomal recessive limb-girdle muscular dystrophy type 2J.
• BP4: Computational evidence support a benign effect (MetaRNN=0.03959641).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
TTN	NM_001267550.2	c.1691C>T	p.Ala564Val	missense_variant	11/363	ENST00000589042.5	NP_001254479.2
TTN	NM_133379.5	c.1691C>T	p.Ala564Val	missense_variant	11/46	ENST00000360870.10	NP_596870.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
TTN	ENST00000589042.5	c.1691C>T	p.Ala564Val	missense_variant	11/363	5	NM_001267550.2	ENSP00000467141	P1
TTN	ENST00000360870.10	c.1691C>T	p.Ala564Val	missense_variant	11/46	5	NM_133379.5	ENSP00000354117

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461796 Hom.: 0 Cov.: 31 AF XY: 0.00000138 AC XY: 1 AN XY: 727212

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: 0.00

Gnomad4 OTH exome AF: 0.0000166

GnomAD4 genome Cov.: 32

Bravo AF: 0.00000378

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

not specified Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine

Mar 28, 2014

The Ala564Val variant in TTN has not been previously reported in individuals wit h cardiomyopathy or in large population studies. Computational prediction tools and conservation analysis suggest that the Ala564Val variant may not impact the protein, though this information is not predictive enough to rule out pathogenic ity. Additional information is needed to fully assess the clinical significance of the Ala564Val variant. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.16
BayesDel_addAF	Benign	-0.30	T
BayesDel_noAF	Benign	-0.68
CADD	Benign	13
DANN	Benign	0.92
Eigen	Benign	-0.79
Eigen_PC	Benign	-0.72
FATHMM_MKL	Benign	0.024	N
LIST_S2	Benign	0.55	T;T;.;T;T
M_CAP	Benign	0.0078	T
MetaRNN	Benign	0.040	T;T;T;T;T
MetaSVM	Benign	-0.99	T
MutationTaster	Benign	1.0	N;N;N;N;N;N;N
PrimateAI	Benign	0.24	T
PROVEAN	Benign	-1.5	N;.;.;.;N
REVEL	Benign	0.065
Sift	Benign	1.0	T;.;.;.;T
Sift4G	Benign	0.25	.;.;.;.;T
Polyphen		0.0, 0.0010	.;.;B;B;B
Vest4		0.15
MutPred		0.42		Gain of loop (P = 0.0013);Gain of loop (P = 0.0013);Gain of loop (P = 0.0013);Gain of loop (P = 0.0013);Gain of loop (P = 0.0013);
MVP		0.076
MPC		0.083
ClinPred		0.096	T
GERP RS		0.86

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.080		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: rs727505068; hg19: chr2-179655544;