NM_001267550.2:c.66054G>A

Variant names:

• chr2-178582402-C-T
• rs727503579
• NM_001267550.2:c.66054G>A

Variant summary

Our verdict is Benign. The variant received -11 ACMG points: 0P and 11B. BP4_Moderate BP6_Very_Strong BP7

The NM_001267550.2(TTN):​c.66054G>A​(p.Glu22018Glu) variant causes a synonymous change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000211 in 1,612,730 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 Likely benign (★★).

• Frequency:
  • Genomes: 𝑓 0.000013 (0 hom., cov: 32)
  • Exomes 𝑓: 0.000022 (0 hom.)
• Consequence: TTN NM_001267550.2 synonymous
• Clinical Significance: Likely benign criteria provided, multiple submitters, no conflicts B:4
• Conservation: PhyloP100: 1.38
• 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: Benign. The variant received -11 ACMG points.

• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.27).
• BP6: Variant 2-178582402-C-T is Benign according to our data. Variant chr2-178582402-C-T is described in ClinVar as [Likely_benign]. Clinvar id is 165890.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.
• BP7: Synonymous conserved (PhyloP=1.38 with no splicing effect.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
TTN	NM_001267550.2	c.66054G>A	p.Glu22018Glu	synonymous_variant	Exon 314 of 363	ENST00000589042.5	NP_001254479.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
TTN	ENST00000589042.5	c.66054G>A	p.Glu22018Glu	synonymous_variant	Exon 314 of 363	5	NM_001267550.2	ENSP00000467141.1

Frequencies

GnomAD3 genomes AF: 0.0000132 AC: 2 AN: 152000 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: 0.0000294

Gnomad OTH AF: 0.00

GnomAD2 exomes AF: 0.00000807 AC: 2 AN: 247914 AF XY: 0.0000149

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: 0.0000178

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.0000219 AC: 32 AN: 1460730 Hom.: 0 Cov.: 32 AF XY: 0.0000193 AC XY: 14 AN XY: 726666

African (AFR) AF: 0.00 AC: 0 AN: 33426

American (AMR) AF: 0.00 AC: 0 AN: 44678

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26112

East Asian (EAS) AF: 0.00 AC: 0 AN: 39518

South Asian (SAS) AF: 0.00 AC: 0 AN: 86198

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53356

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5758

European-Non Finnish (NFE) AF: 0.0000288 AC: 32 AN: 1111370

Other (OTH) AF: 0.00 AC: 0 AN: 60314

GnomAD4 genome AF: 0.0000132 AC: 2 AN: 152000 Hom.: 0 Cov.: 32 AF XY: 0.0000135 AC XY: 1 AN XY: 74206

African (AFR) AF: 0.00 AC: 0 AN: 41394

American (AMR) AF: 0.00 AC: 0 AN: 15252

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 3466

East Asian (EAS) AF: 0.00 AC: 0 AN: 5156

South Asian (SAS) AF: 0.00 AC: 0 AN: 4828

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10612

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

European-Non Finnish (NFE) AF: 0.0000294 AC: 2 AN: 67976

Other (OTH) AF: 0.00 AC: 0 AN: 2088

Alfa AF: 0.0000329 Hom.: 0

Bravo AF: 0.0000227

EpiCase AF: 0.0000546

EpiControl AF: 0.00

ClinVar

Significance: Likely benign

Submissions summary: Benign:4

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not specified Benign:1

Apr 09, 2013

Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine

Significance: Likely benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Glu19450Glu in exon 263 of TTN: This variant is not expected to have clinical si gnificance because it does not alter an amino acid residue and is not located wi thin the splice consensus sequence. Glu19450Glu in exon 263 of TTN (allele freq uency = n/a) -

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

Jan 26, 2025

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Likely benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Autosomal recessive limb-girdle muscular dystrophy type 2J;C1838244:Tibial muscular dystrophy;C1858763:Dilated cardiomyopathy 1G;C1861065:Hypertrophic cardiomyopathy 9;C1863599:Myopathy, myofibrillar, 9, with early respiratory failure;C2673677:Early-onset myopathy with fatal cardiomyopathy Benign:1

Aug 27, 2021

Fulgent Genetics, Fulgent Genetics

Significance: Likely benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Cardiovascular phenotype Benign:1

Oct 03, 2020

Ambry Genetics

Significance: Likely benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This alteration is classified as likely benign based on a combination of the following: seen in unaffected individuals, population frequency, intact protein function, lack of segregation with disease, co-occurrence, RNA analysis, in silico models, amino acid conservation, lack of disease association in case-control studies, and/or the mechanism of disease or impacted region is inconsistent with a known cause of pathogenicity. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.27
CADD	Benign	1.3
DANN	Benign	0.82
PhyloP100		1.4
Mutation Taster		=43/57	disease causing

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: rs727503579; hg19: chr2-179447129;