2-178713964-C-A

Variant names:

• chr2-178713964-C-A
• rs199525540
• NM_001267550.2:c.26694G>T

Variant summary

Our verdict is Likely benign. The variant received -6 ACMG points: 0P and 6B. BP4_Strong BP6 BP7

The NM_001267550.2(TTN):​c.26694G>T​(p.Gly8898Gly) variant causes a synonymous change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000716 in 1,613,576 control chromosomes in the GnomAD database, including 1 homozygotes. In-silico tool predicts 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. G8898G) has been classified as Likely benign.

• Frequency:
  • Genomes: 𝑓 0.00040 (0 hom., cov: 33)
  • Exomes 𝑓: 0.00075 (1 hom.)
• Consequence: TTN NM_001267550.2 synonymous
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:3 B:13
• Conservation: PhyloP100: -1.18
• 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]

LOC124906100 (HGNC:):

ACMG classification

Our verdict: Likely_benign. The variant received -6 ACMG points.

• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.55).
• BP6: Variant 2-178713964-C-A is Benign according to our data. Variant chr2-178713964-C-A is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 166143.
• BP7: Synonymous conserved (PhyloP=-1.17 with no splicing effect.

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

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	TTN	NM_001267550.2	MANE Select	c.26694G>T	p.Gly8898Gly	synonymous	Exon 92 of 363	NP_001254479.2	Q8WZ42-12
	TTN	NM_001256850.1		c.25743G>T	p.Gly8581Gly	synonymous	Exon 90 of 313	NP_001243779.1	Q8WZ42-1
	TTN	NM_133378.4		c.22962G>T	p.Gly7654Gly	synonymous	Exon 89 of 312	NP_596869.4	Q8WZ42-11

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	TTN	ENST00000589042.5	TSL:5 MANE Select	c.26694G>T	p.Gly8898Gly	synonymous	Exon 92 of 363	ENSP00000467141.1	Q8WZ42-12
	TTN	ENST00000446966.2	TSL:1	c.26694G>T	p.Gly8898Gly	synonymous	Exon 92 of 361	ENSP00000408004.2	A0A1B0GXE3
	TTN	ENST00000436599.2	TSL:1	c.26418G>T	p.Gly8806Gly	synonymous	Exon 90 of 361	ENSP00000405517.2	A0A0C4DG59

Frequencies

GnomAD3 genomes AF: 0.000401 AC: 61 AN: 152088 Hom.: 0 Cov.: 33

Gnomad AFR AF: 0.0000724

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.000458

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00104

Gnomad FIN AF: 0.000189

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.000603

Gnomad OTH AF: 0.00144

GnomAD2 exomes AF: 0.000567 AC: 141 AN: 248788 AF XY: 0.000615

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.000465

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad FIN exome AF: 0.0000464

Gnomad NFE exome AF: 0.000683

Gnomad OTH exome AF: 0.000663

GnomAD4 exome AF: 0.000749 AC: 1094 AN: 1461370 Hom.: 1 Cov.: 31 AF XY: 0.000750 AC XY: 545 AN XY: 726944

African (AFR) AF: 0.0000598 AC: 2 AN: 33462

American (AMR) AF: 0.000604 AC: 27 AN: 44698

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26128

East Asian (EAS) AF: 0.00 AC: 0 AN: 39676

South Asian (SAS) AF: 0.00136 AC: 117 AN: 86234

European-Finnish (FIN) AF: 0.000131 AC: 7 AN: 53384

Middle Eastern (MID) AF: 0.000173 AC: 1 AN: 5764

European-Non Finnish (NFE) AF: 0.000808 AC: 898 AN: 1111676

Other (OTH) AF: 0.000696 AC: 42 AN: 60348

GnomAD4 genome AF: 0.000401 AC: 61 AN: 152206 Hom.: 0 Cov.: 33 AF XY: 0.000349 AC XY: 26 AN XY: 74412

African (AFR) AF: 0.0000722 AC: 3 AN: 41546

American (AMR) AF: 0.000458 AC: 7 AN: 15290

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 3470

East Asian (EAS) AF: 0.00 AC: 0 AN: 5170

South Asian (SAS) AF: 0.00104 AC: 5 AN: 4814

European-Finnish (FIN) AF: 0.000189 AC: 2 AN: 10604

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 294

European-Non Finnish (NFE) AF: 0.000603 AC: 41 AN: 67996

Other (OTH) AF: 0.00142 AC: 3 AN: 2110

Alfa AF: 0.000411 Hom.: 0

Bravo AF: 0.000404

Asia WGS AF: 0.000289 AC: 1 AN: 3476

EpiCase AF: 0.000982

EpiControl AF: 0.000890

ClinVar

ClinVar submissions

Significance: Conflicting classifications of pathogenicity

Revision: criteria provided, conflicting classifications

Pathogenic	VUS	Benign	Condition
-	-	6	not specified (6)
-	-	4	not provided (4)
-	1	-	Autosomal recessive limb-girdle muscular dystrophy type 2J (1)
-	-	1	Autosomal recessive limb-girdle muscular dystrophy type 2J;C1858763:Dilated cardiomyopathy 1G (1)
-	1	-	Dilated cardiomyopathy 1G (1)
-	1	-	Early-onset myopathy with fatal cardiomyopathy (1)
-	-	1	Myopathy, myofibrillar, 9, with early respiratory failure (1)
-	-	1	Tibial muscular dystrophy (1)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.55
CADD	Benign	0.29
DANN	Benign	0.69
PhyloP100		-1.2
Mutation Taster		=94/6	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: rs199525540; hg19: chr2-179578691;