chr2-178575951-G-A

Variant names:

• chr2-178575951-G-A
• rs397517683
• NM_001267550.2:c.70181C>T

Variant summary

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

The NM_001267550.2(TTN):​c.70181C>T​(p.Thr23394Met) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.0000316 in 1,611,452 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 (★★). Synonymous variant affecting the same amino acid position (i.e. T23394T) has been classified as Likely benign.

• Frequency:
  • Genomes: 𝑓 0.000013 (0 hom., cov: 32)
  • Exomes 𝑓: 0.000034 (0 hom.)
• Consequence: TTN NM_001267550.2 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:11
• Conservation: PhyloP100: 9.94
• Publications: 3 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=0.3801462).

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.70181C>T	p.Thr23394Met	missense	Exon 326 of 363	NP_001254479.2	Q8WZ42-12
	TTN	NM_001256850.1		c.65258C>T	p.Thr21753Met	missense	Exon 276 of 313	NP_001243779.1	Q8WZ42-1
	TTN	NM_133378.4		c.62477C>T	p.Thr20826Met	missense	Exon 275 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.70181C>T	p.Thr23394Met	missense	Exon 326 of 363	ENSP00000467141.1	Q8WZ42-12
	TTN	ENST00000446966.2	TSL:1	c.70025C>T	p.Thr23342Met	missense	Exon 324 of 361	ENSP00000408004.2	A0A1B0GXE3
	TTN	ENST00000436599.2	TSL:1	c.69905C>T	p.Thr23302Met	missense	Exon 324 of 361	ENSP00000405517.2	A0A0C4DG59

Frequencies

GnomAD3 genomes AF: 0.0000132 AC: 2 AN: 152048 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: 0.000194

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.0000147

Gnomad OTH AF: 0.00

GnomAD2 exomes AF: 0.0000241 AC: 6 AN: 248588 AF XY: 0.0000222

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.0000870

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.0000557

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.0000178

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.0000336 AC: 49 AN: 1459404 Hom.: 0 Cov.: 36 AF XY: 0.0000345 AC XY: 25 AN XY: 725534

African (AFR) AF: 0.00 AC: 0 AN: 33422

American (AMR) AF: 0.0000671 AC: 3 AN: 44678

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26116

East Asian (EAS) AF: 0.0000505 AC: 2 AN: 39632

South Asian (SAS) AF: 0.0000116 AC: 1 AN: 86194

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53330

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5750

European-Non Finnish (NFE) AF: 0.0000387 AC: 43 AN: 1110004

Other (OTH) AF: 0.00 AC: 0 AN: 60278

GnomAD4 genome AF: 0.0000132 AC: 2 AN: 152048 Hom.: 0 Cov.: 32 AF XY: 0.0000269 AC XY: 2 AN XY: 74254

African (AFR) AF: 0.00 AC: 0 AN: 41432

American (AMR) AF: 0.00 AC: 0 AN: 15260

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

East Asian (EAS) AF: 0.000194 AC: 1 AN: 5156

South Asian (SAS) AF: 0.00 AC: 0 AN: 4820

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10608

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

European-Non Finnish (NFE) AF: 0.0000147 AC: 1 AN: 67988

Other (OTH) AF: 0.00 AC: 0 AN: 2084

Alfa AF: 0.0000580 Hom.: 0

Bravo AF: 0.0000151

TwinsUK AF: 0.000270 AC: 1

ALSPAC AF: 0.00 AC: 0

ExAC AF: 0.0000248 AC: 3

ClinVar

ClinVar submissions

Significance: Uncertain significance

Revision: criteria provided, multiple submitters, no conflicts

Pathogenic	VUS	Benign	Condition
-	6	-	not provided (6)
-	1	-	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 (1)
-	1	-	Autosomal recessive limb-girdle muscular dystrophy type 2J;C1858763:Dilated cardiomyopathy 1G (1)
-	1	-	Cardiomyopathy (1)
-	1	-	Cardiovascular phenotype (1)
-	1	-	not specified (1)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Uncertain	0.41
BayesDel_addAF	Benign	-0.015	T
BayesDel_noAF	Uncertain	-0.060
CADD	Uncertain	23
DANN	Benign	0.91
Eigen	Pathogenic	1.0
Eigen_PC	Pathogenic	0.96
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Pathogenic	0.98	D
M_CAP	Benign	0.043	D
MetaRNN	Benign	0.38	T
MetaSVM	Uncertain	0.26	D
MutationAssessor	Pathogenic	3.7	H
PhyloP100		9.9
PrimateAI	Uncertain	0.79	T
PROVEAN	Pathogenic	-4.4	D
REVEL	Uncertain	0.50
Sift	Uncertain	0.0020	D
Polyphen		1.0	D
Vest4		0.38
MutPred		0.47		Loss of catalytic residue at F21756 (P = 0.0891)
MVP		0.66
MPC		0.47
ClinPred		0.37	T
GERP RS		5.6
Mutation Taster		=84/16	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: rs397517683; hg19: chr2-179440678; COSMIC: COSV59895689; COSMIC: COSV59895689;