chr2-178775872-G-A

Variant names:

• chr2-178775872-G-A
• rs727503692
• NM_001267550.2:c.5992C>T

Variant summary

Our verdict is Likely benign. The variant received -1 ACMG points: 0P and 1B. BP4

The NM_001267550.2(TTN):​c.5992C>T​(p.Arg1998Cys) variant causes a missense change. The variant allele was found at a frequency of 0.00000616 in 1,461,834 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R1998H) has been classified as Likely benign.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0000062 (0 hom.)
• Consequence: TTN NM_001267550.2 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: 6.13
• Publications: 5 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 -1 ACMG points.

• BP4: Computational evidence support a benign effect (MetaRNN=0.3880654).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
TTN	NM_001267550.2	c.5992C>T	p.Arg1998Cys	missense_variant	Exon 28 of 363	ENST00000589042.5	NP_001254479.2
TTN	NM_133379.5	c.5992C>T	p.Arg1998Cys	missense_variant	Exon 28 of 46	ENST00000360870.10	NP_596870.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
TTN	ENST00000589042.5	c.5992C>T	p.Arg1998Cys	missense_variant	Exon 28 of 363	5	NM_001267550.2	ENSP00000467141.1
TTN	ENST00000360870.10	c.5992C>T	p.Arg1998Cys	missense_variant	Exon 28 of 46	5	NM_133379.5	ENSP00000354117.4

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD2 exomes AF: 0.00 AC: 0 AN: 250982 AF XY: 0.00

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: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000616 AC: 9 AN: 1461834 Hom.: 0 Cov.: 33 AF XY: 0.00000550 AC XY: 4 AN XY: 727220

African (AFR) AF: 0.00 AC: 0 AN: 33474

American (AMR) AF: 0.0000224 AC: 1 AN: 44720

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26134

East Asian (EAS) AF: 0.00 AC: 0 AN: 39696

South Asian (SAS) AF: 0.00 AC: 0 AN: 86256

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53414

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5768

European-Non Finnish (NFE) AF: 0.00000719 AC: 8 AN: 1111978

Other (OTH) AF: 0.00 AC: 0 AN: 60394

GnomAD4 genome Cov.: 33

Alfa AF: 0.00 Hom.: 0

Bravo AF: 0.0000113

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not specified Uncertain:1

Nov 25, 2015

Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

proposed classification - variant undergoing re-assessment, contact laboratory -

not provided Uncertain:1

Jun 26, 2024

Mayo Clinic Laboratories, Mayo Clinic

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	Uncertain	0.41
BayesDel_addAF	Pathogenic	0.17	D
BayesDel_noAF	Uncertain	0.0
CADD	Pathogenic	29
DANN	Uncertain	0.98
Eigen	Uncertain	0.61
Eigen_PC	Uncertain	0.63
FATHMM_MKL	Uncertain	0.95	D
LIST_S2	Pathogenic	0.99	D;D;D;.;D;D;D;D
M_CAP	Benign	0.050	D
MetaRNN	Benign	0.39	T;T;T;T;T;T;T;T
MetaSVM	Uncertain	-0.20	T
PhyloP100		6.1
PrimateAI	Uncertain	0.76	T
PROVEAN	Pathogenic	-5.1	D;D;.;.;D;D;.;D
REVEL	Uncertain	0.40
Sift	Uncertain	0.0050	D;D;.;.;D;D;.;D
Sift4G	Pathogenic	0.0	.;.;.;.;.;.;.;D
Polyphen		1.0	.;.;.;D;.;.;D;D
Vest4		0.48
MutPred		0.36		Loss of MoRF binding (P = 0.0316);.;Loss of MoRF binding (P = 0.0316);Loss of MoRF binding (P = 0.0316);.;.;Loss of MoRF binding (P = 0.0316);Loss of MoRF binding (P = 0.0316);
MVP		0.66
MPC		0.46
ClinPred		0.88	D
GERP RS		5.1
Mutation Taster		=82/18	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: rs727503692; hg19: chr2-179640599; COSMIC: COSV59943987; COSMIC: COSV59943987;