2-178776666-G-A

Variant names:

• chr2-178776666-G-A
• rs367700246
• NM_001267550.2:c.5198C>T

Variant summary

Our verdict is Likely benign. The variant received -5 ACMG points: 0P and 5B. BP4_Strong BP6

The NM_001267550.2(TTN):​c.5198C>T​(p.Thr1733Met) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.000135 in 1,613,978 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 Conflicting classifications of pathogenicity (no stars). Synonymous variant affecting the same amino acid position (i.e. T1733T) has been classified as Likely benign.

• Frequency:
  • Genomes: 𝑓 0.00013 (0 hom., cov: 32)
  • Exomes 𝑓: 0.00014 (0 hom.)
• Consequence: TTN NM_001267550.2 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:6 B:7
• Conservation: PhyloP100: 7.98
• Publications: 7 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 -5 ACMG points.

• BP4: Computational evidence support a benign effect (MetaRNN=0.031618744).
• BP6: Variant 2-178776666-G-A is Benign according to our data. Variant chr2-178776666-G-A is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 166316.

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.5198C>T	p.Thr1733Met	missense	Exon 28 of 363	NP_001254479.2	Q8WZ42-12
	TTN	NM_001256850.1		c.5198C>T	p.Thr1733Met	missense	Exon 28 of 313	NP_001243779.1	Q8WZ42-1
	TTN	NM_133378.4		c.5198C>T	p.Thr1733Met	missense	Exon 28 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.5198C>T	p.Thr1733Met	missense	Exon 28 of 363	ENSP00000467141.1	Q8WZ42-12
	TTN	ENST00000446966.2	TSL:1	c.5198C>T	p.Thr1733Met	missense	Exon 28 of 361	ENSP00000408004.2	A0A1B0GXE3
	TTN	ENST00000436599.2	TSL:1	c.4922C>T	p.Thr1641Met	missense	Exon 26 of 361	ENSP00000405517.2	A0A0C4DG59

Frequencies

GnomAD3 genomes AF: 0.000131 AC: 20 AN: 152198 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.00461

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.000414

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.0000294

Gnomad OTH AF: 0.00

GnomAD2 exomes AF: 0.000303 AC: 76 AN: 250784 AF XY: 0.000251

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.000347

Gnomad ASJ exome AF: 0.00427

Gnomad EAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.000106

Gnomad OTH exome AF: 0.000981

GnomAD4 exome AF: 0.000135 AC: 198 AN: 1461780 Hom.: 0 Cov.: 33 AF XY: 0.000136 AC XY: 99 AN XY: 727194

African (AFR) AF: 0.00 AC: 0 AN: 33472

American (AMR) AF: 0.000313 AC: 14 AN: 44710

Ashkenazi Jewish (ASJ) AF: 0.00455 AC: 119 AN: 26134

East Asian (EAS) AF: 0.0000504 AC: 2 AN: 39662

South Asian (SAS) AF: 0.0000580 AC: 5 AN: 86258

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53406

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5768

European-Non Finnish (NFE) AF: 0.0000324 AC: 36 AN: 1111980

Other (OTH) AF: 0.000364 AC: 22 AN: 60390

GnomAD4 genome AF: 0.000131 AC: 20 AN: 152198 Hom.: 0 Cov.: 32 AF XY: 0.000121 AC XY: 9 AN XY: 74356

African (AFR) AF: 0.00 AC: 0 AN: 41452

American (AMR) AF: 0.00 AC: 0 AN: 15284

Ashkenazi Jewish (ASJ) AF: 0.00461 AC: 16 AN: 3470

East Asian (EAS) AF: 0.00 AC: 0 AN: 5190

South Asian (SAS) AF: 0.000414 AC: 2 AN: 4828

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10620

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

European-Non Finnish (NFE) AF: 0.0000294 AC: 2 AN: 68034

Other (OTH) AF: 0.00 AC: 0 AN: 2092

Alfa AF: 0.000581 Hom.: 0

Bravo AF: 0.000155

ESP6500AA AF: 0.00 AC: 0

ESP6500EA AF: 0.000116 AC: 1

ExAC AF: 0.000239 AC: 29

EpiCase AF: 0.000164

EpiControl AF: 0.000296

ClinVar

ClinVar submissions

Significance: Conflicting classifications of pathogenicity

Revision: criteria provided, conflicting classifications

Pathogenic	VUS	Benign	Condition
-	1	2	not specified (3)
-	2	-	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	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
AlphaMissense	Benign	0.29
BayesDel_addAF	Benign	0.0086	T
BayesDel_noAF	Uncertain	0.070
CADD	Pathogenic	26
DANN	Benign	0.90
Eigen	Pathogenic	0.73
Eigen_PC	Pathogenic	0.72
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Pathogenic	0.98	D
M_CAP	Benign	0.043	D
MetaRNN	Benign	0.032	T
MetaSVM	Uncertain	-0.081	T
PhyloP100		8.0
PrimateAI	Uncertain	0.65	T
PROVEAN	Uncertain	-4.1	D
REVEL	Uncertain	0.61
Sift	Uncertain	0.0040	D
Sift4G	Uncertain	0.0020	D
Polyphen		1.0	D
Vest4		0.36
MVP		0.69
MPC		0.47
ClinPred		0.086	T
GERP RS		5.0
Mutation Taster		=85/15	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: rs367700246; hg19: chr2-179641393; COSMIC: COSV60065385; COSMIC: COSV60065385;