chr2-178774941-G-C

Position:

• chr2-178774941-G-C

Variant summary

Our verdict is Likely benign. Variant got -4 ACMG points: 1P and 5B. PP2 BP4_Strong BP6

The NM_001267550.2(TTN):​c.6770C>G​(p.Thr2257Ser) variant causes a missense change. The variant allele was found at a frequency of 0.0000174 in 1,613,666 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 12/18 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars). Synonymous variant affecting the same amino acid position (i.e. T2257T) has been classified as Likely benign.

• Frequency:
  • Genomes: 𝑓 0.000039 (0 hom., cov: 32)
  • Exomes 𝑓: 0.000015 (0 hom.)
• Consequence: TTN NM_001267550.2 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:1 B:1
• Conservation: PhyloP100: 6.41

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:):

ACMG classification

Verdict is Likely_benign. Variant got -4 ACMG points.

• 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=0.0536125).
• BP6: Variant 2-178774941-G-C is Benign according to our data. Variant chr2-178774941-G-C is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 192074.We mark this variant Likely_benign, oryginal submissions are: {Likely_benign=1, Uncertain_significance=1}.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
TTN	NM_001267550.2	c.6770C>G	p.Thr2257Ser	missense_variant	29/363	ENST00000589042.5	NP_001254479.2
TTN	NM_133379.5	c.6770C>G	p.Thr2257Ser	missense_variant	29/46	ENST00000360870.10	NP_596870.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
TTN	ENST00000589042.5	c.6770C>G	p.Thr2257Ser	missense_variant	29/363	5	NM_001267550.2	ENSP00000467141.1
TTN	ENST00000360870.10	c.6770C>G	p.Thr2257Ser	missense_variant	29/46	5	NM_133379.5	ENSP00000354117.4

Frequencies

GnomAD3 genomes AF: 0.0000394 AC: 6 AN: 152188 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: 0.000578

Gnomad SAS AF: 0.000207

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.0000147

Gnomad OTH AF: 0.000478

GnomAD3 exomes AF: 0.0000678 AC: 17 AN: 250680 Hom.: 0 AF XY: 0.0000812 AC XY: 11 AN XY: 135476

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.000873

Gnomad SAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.000164

GnomAD4 exome AF: 0.0000151 AC: 22 AN: 1461478 Hom.: 0 Cov.: 33 AF XY: 0.0000234 AC XY: 17 AN XY: 727042

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.000277

Gnomad4 SAS exome AF: 0.0000928

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00

Gnomad4 OTH exome AF: 0.0000497

GnomAD4 genome AF: 0.0000394 AC: 6 AN: 152188 Hom.: 0 Cov.: 32 AF XY: 0.0000269 AC XY: 2 AN XY: 74338

Gnomad4 AFR AF: 0.00

Gnomad4 AMR AF: 0.00

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.000578

Gnomad4 SAS AF: 0.000207

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.0000147

Gnomad4 OTH AF: 0.000478

Bravo AF: 0.0000378

ExAC AF: 0.0000659 AC: 8

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:1 Benign:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

not provided Uncertain:1

Uncertain significance, criteria provided, single submitter

research

Biesecker Lab/Clinical Genomics Section, National Institutes of Health

Jun 24, 2013

- -

Autosomal recessive limb-girdle muscular dystrophy type 2J;C1858763:Dilated cardiomyopathy 1G Benign:1

Likely benign, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Dec 06, 2023

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.099
BayesDel_addAF	Benign	-0.42	T
BayesDel_noAF	Benign	-0.45
CADD	Benign	21
DANN	Benign	0.92
Eigen	Benign	0.18
Eigen_PC	Uncertain	0.34
FATHMM_MKL	Uncertain	0.95	D
LIST_S2	Benign	0.78	T;T;T;.;T;T;T;T
M_CAP	Benign	0.023	T
MetaRNN	Benign	0.054	T;T;T;T;T;T;T;T
MetaSVM	Benign	-1.0	T
PrimateAI	Benign	0.44	T
PROVEAN	Benign	-1.9	N;N;.;.;N;N;.;D
REVEL	Benign	0.21
Sift	Benign	0.64	T;T;.;.;T;T;.;T
Sift4G	Benign	0.32	.;.;.;.;.;.;.;T
Polyphen		0.78, 0.88	.;.;.;P;.;.;P;P
Vest4		0.33
MutPred		0.41		Loss of ubiquitination at K2259 (P = 0.0863);.;Loss of ubiquitination at K2259 (P = 0.0863);Loss of ubiquitination at K2259 (P = 0.0863);.;.;Loss of ubiquitination at K2259 (P = 0.0863);Loss of ubiquitination at K2259 (P = 0.0863);
MVP		0.085
MPC		0.12
ClinPred		0.086	T
GERP RS		5.6

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.060		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: rs755999681; hg19: chr2-179639668;