2-178709854-G-T

Variant names:

• chr2-178709854-G-T
• rs200489972
• NM_001267550.2:c.28465C>A

Variant summary

Our verdict is Benign. The variant received -8 ACMG points: 2P and 10B. PM2 BP4_Moderate BP6_Very_Strong

The NM_001267550.2(TTN):​c.28465C>A​(p.Arg9489Arg) variant causes a splice region, synonymous change. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a benign outcome for this variant. 1/1 splice prediction tools predict no significant impact on normal splicing. Variant has been reported in ClinVar as Likely benign (★★). Synonymous variant affecting the same amino acid position (i.e. R9489R) has been classified as Likely benign.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0 (0 hom.)
  • Failed GnomAD Quality Control
• Consequence: TTN NM_001267550.2 splice_region, synonymous
• Clinical Significance: Likely benign criteria provided, multiple submitters, no conflicts B:2
• Conservation: PhyloP100: 5.86
• Publications: 1 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]

LOC124906100 (HGNC:):

ACMG classification

Our verdict: Benign. The variant received -8 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.25).
• BP6: Variant 2-178709854-G-T is Benign according to our data. Variant chr2-178709854-G-T is described in ClinVar as Likely_benign. ClinVar VariationId is 508719.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_001267550.2. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	TTN	NM_001267550.2	MANE Select	c.28465C>A	p.Arg9489Arg	splice_region synonymous	Exon 99 of 363	NP_001254479.2
	TTN	NM_001256850.1		c.27514C>A	p.Arg9172Arg	splice_region synonymous	Exon 97 of 313	NP_001243779.1
	TTN	NM_133378.4		c.24733C>A	p.Arg8245Arg	splice_region synonymous	Exon 96 of 312	NP_596869.4

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	TTN	ENST00000589042.5	TSL:5 MANE Select	c.28465C>A	p.Arg9489Arg	splice_region synonymous	Exon 99 of 363	ENSP00000467141.1
	TTN	ENST00000446966.2	TSL:1	c.28465C>A	p.Arg9489Arg	splice_region synonymous	Exon 99 of 361	ENSP00000408004.2
	TTN	ENST00000436599.2	TSL:1	c.28189C>A	p.Arg9397Arg	splice_region synonymous	Exon 97 of 361	ENSP00000405517.2

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Data not reliable, filtered out with message: AC0 AF: 0.00 AC: 0 AN: 1455324 Hom.: 0 Cov.: 31 AF XY: 0.00 AC XY: 0 AN XY: 723210

African (AFR) AF: 0.00 AC: 0 AN: 33196

American (AMR) AF: 0.00 AC: 0 AN: 44380

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26022

East Asian (EAS) AF: 0.00 AC: 0 AN: 39606

South Asian (SAS) AF: 0.00 AC: 0 AN: 85782

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 52274

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5744

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 1108208

Other (OTH) AF: 0.00 AC: 0 AN: 60112

GnomAD4 genome Cov.: 33

ClinVar

Significance: Likely benign

Submissions summary: Benign:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not specified Benign:1

Mar 31, 2017

GeneDx

Significance: Likely benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant is considered likely benign or benign based on one or more of the following criteria: it is a conservative change, it occurs at a poorly conserved position in the protein, it is predicted to be benign by multiple in silico algorithms, and/or has population frequency not consistent with disease.

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

Aug 10, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Likely benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.25
CADD	Benign	9.2
DANN	Benign	0.75
PhyloP100		5.9
Mutation Taster		=24/76	disease causing

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.020		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: rs200489972; hg19: chr2-179574581;