NM_001267550.2:c.62943T>C

Variant names:

• chr2-178588782-A-G
• rs184863287
• NM_001267550.2:c.62943T>C

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.62943T>C​(p.Thr20981Thr) variant causes a synonymous change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000423 in 1,613,382 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).

• Frequency:
  • Genomes: 𝑓 0.00030 (0 hom., cov: 32)
  • Exomes 𝑓: 0.00044 (1 hom.)
• Consequence: TTN NM_001267550.2 synonymous
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:4 B:11
• Conservation: PhyloP100: -0.00600
• 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 -6 ACMG points.

• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.56).
• BP6: Variant 2-178588782-A-G is Benign according to our data. Variant chr2-178588782-A-G is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 165912.
• BP7: Synonymous conserved (PhyloP=-0.006 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.62943T>C	p.Thr20981Thr	synonymous	Exon 304 of 363	NP_001254479.2	Q8WZ42-12
	TTN	NM_001256850.1		c.58020T>C	p.Thr19340Thr	synonymous	Exon 254 of 313	NP_001243779.1	Q8WZ42-1
	TTN	NM_133378.4		c.55239T>C	p.Thr18413Thr	synonymous	Exon 253 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.62943T>C	p.Thr20981Thr	synonymous	Exon 304 of 363	ENSP00000467141.1	Q8WZ42-12
	TTN	ENST00000446966.2	TSL:1	c.62787T>C	p.Thr20929Thr	synonymous	Exon 302 of 361	ENSP00000408004.2	A0A1B0GXE3
	TTN	ENST00000436599.2	TSL:1	c.62667T>C	p.Thr20889Thr	synonymous	Exon 302 of 361	ENSP00000405517.2	A0A0C4DG59

Frequencies

GnomAD3 genomes AF: 0.000302 AC: 46 AN: 152090 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.000217

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: 0.000529

Gnomad OTH AF: 0.000478

GnomAD2 exomes AF: 0.000197 AC: 49 AN: 248362 AF XY: 0.000200

Gnomad AFR exome AF: 0.000194

Gnomad AMR exome AF: 0.0000290

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.000400

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.000436 AC: 637 AN: 1461174 Hom.: 1 Cov.: 33 AF XY: 0.000398 AC XY: 289 AN XY: 726872

African (AFR) AF: 0.000149 AC: 5 AN: 33448

American (AMR) AF: 0.0000224 AC: 1 AN: 44684

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26110

East Asian (EAS) AF: 0.00 AC: 0 AN: 39604

South Asian (SAS) AF: 0.00 AC: 0 AN: 86224

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53370

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5756

European-Non Finnish (NFE) AF: 0.000525 AC: 584 AN: 1111628

Other (OTH) AF: 0.000779 AC: 47 AN: 60350

GnomAD4 genome AF: 0.000302 AC: 46 AN: 152208 Hom.: 0 Cov.: 32 AF XY: 0.000175 AC XY: 13 AN XY: 74408

African (AFR) AF: 0.000217 AC: 9 AN: 41564

American (AMR) AF: 0.00 AC: 0 AN: 15276

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 3472

East Asian (EAS) AF: 0.00 AC: 0 AN: 5144

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

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10624

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

European-Non Finnish (NFE) AF: 0.000530 AC: 36 AN: 67982

Other (OTH) AF: 0.000473 AC: 1 AN: 2116

Alfa AF: 0.000319 Hom.: 0

Bravo AF: 0.000287

EpiCase AF: 0.000273

EpiControl AF: 0.000237

ClinVar

ClinVar submissions

Significance: Conflicting classifications of pathogenicity

Revision: criteria provided, conflicting classifications

Pathogenic	VUS	Benign	Condition
-	-	4	not specified (4)
-	1	1	not provided (2)
-	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	Cardiomyopathy (1)
-	-	1	Cardiovascular phenotype (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)
-	-	1	TTN-related disorder (1)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.56
CADD	Benign	0.33
DANN	Benign	0.77
PhyloP100		-0.0060
Mutation Taster		=80/20	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: rs184863287; hg19: chr2-179453509;