2-178605654-G-C

Variant names:

• chr2-178605654-G-C
• rs771801125
• NM_001267550.2:c.53641C>G

Variant summary

Our verdict is Likely benign. The variant received -3 ACMG points: 0P and 3B. BP4_Moderate BP6

The NM_001267550.2(TTN):​c.53641C>G​(p.Leu17881Val) variant causes a missense change. The variant allele was found at a frequency of 0.00000808 in 1,609,800 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 14/20 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. L17881F) has been classified as Uncertain significance.

• Frequency:
  • Genomes: 𝑓 0.0000066 (0 hom., cov: 32)
  • Exomes 𝑓: 0.0000082 (0 hom.)
• Consequence: TTN NM_001267550.2 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:1 B:1
• Conservation: PhyloP100: 4.09
• 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 -3 ACMG points.

• BP4: Computational evidence support a benign effect (MetaRNN=0.24307248).
• BP6: Variant 2-178605654-G-C is Benign according to our data. Variant chr2-178605654-G-C is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 404849.We mark this variant Likely_benign, oryginal submission is: [Conflicting_classifications_of_pathogenicity].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
TTN	NM_001267550.2	c.53641C>G	p.Leu17881Val	missense_variant	Exon 279 of 363	ENST00000589042.5	NP_001254479.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
TTN	ENST00000589042.5	c.53641C>G	p.Leu17881Val	missense_variant	Exon 279 of 363	5	NM_001267550.2	ENSP00000467141.1

Frequencies

GnomAD3 genomes AF: 0.00000658 AC: 1 AN: 151976 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

GnomAD2 exomes AF: 0.00000810 AC: 2 AN: 246822 AF XY: 0.00000747

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: 0.00000895

Gnomad OTH exome AF: 0.000167

GnomAD4 exome AF: 0.00000823 AC: 12 AN: 1457824 Hom.: 0 Cov.: 32 AF XY: 0.00000690 AC XY: 5 AN XY: 724942

African (AFR) AF: 0.00 AC: 0 AN: 33336

American (AMR) AF: 0.00 AC: 0 AN: 44590

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26006

East Asian (EAS) AF: 0.00 AC: 0 AN: 39510

South Asian (SAS) AF: 0.00 AC: 0 AN: 85798

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53264

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5752

European-Non Finnish (NFE) AF: 0.00000992 AC: 11 AN: 1109374

Other (OTH) AF: 0.0000166 AC: 1 AN: 60194

GnomAD4 genome AF: 0.00000658 AC: 1 AN: 151976 Hom.: 0 Cov.: 32 AF XY: 0.00 AC XY: 0 AN XY: 74216

African (AFR) AF: 0.00 AC: 0 AN: 41436

American (AMR) AF: 0.00 AC: 0 AN: 15246

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

East Asian (EAS) AF: 0.00 AC: 0 AN: 5136

South Asian (SAS) AF: 0.00 AC: 0 AN: 4824

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10608

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

European-Non Finnish (NFE) AF: 0.0000147 AC: 1 AN: 67944

Other (OTH) AF: 0.00 AC: 0 AN: 2086

Alfa AF: 0.0000434 Hom.: 0

Bravo AF: 0.0000151

ExAC AF: 0.00000828 AC: 1

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:1 Benign:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

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

Dec 05, 2016

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Cardiomyopathy Benign:1

May 16, 2023

CHEO Genetics Diagnostic Laboratory, Children's Hospital of Eastern Ontario

Significance: Likely benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.24
BayesDel_addAF	Benign	-0.050	T
BayesDel_noAF	Benign	-0.31
CADD	Benign	18
DANN	Benign	0.84
Eigen	Uncertain	0.19
Eigen_PC	Benign	0.21
FATHMM_MKL	Pathogenic	0.97	D
LIST_S2	Uncertain	0.91	D;D;D;.;D;D;D
M_CAP	Benign	0.017	T
MetaRNN	Benign	0.24	T;T;T;T;T;T;T
MetaSVM	Benign	-0.61	T
MutationAssessor	Benign	1.8	.;.;.;L;.;.;L
PhyloP100		4.1
PrimateAI	Uncertain	0.50	T
PROVEAN	Benign	-2.2	N;N;.;.;N;N;.
REVEL	Benign	0.25
Sift	Benign	0.15	T;D;.;.;D;D;.
Polyphen		0.90	.;.;.;P;.;.;P
Vest4		0.37
MutPred		0.66		.;.;.;Loss of catalytic residue at L16240 (P = 0.0026);.;.;Loss of catalytic residue at L16240 (P = 0.0026);
MVP		0.33
MPC		0.24
ClinPred		0.18	T
GERP RS		4.8
Mutation Taster		=89/11	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: rs771801125; hg19: chr2-179470381;