NM_001267550.2:c.76739C>T

Variant names:

• chr2-178569393-G-A
• rs56372592
• NM_001267550.2:c.76739C>T

Variant summary

Our verdict is Benign. The variant received -20 ACMG points: 0P and 20B. BP4_Strong BP6_Very_Strong BS1 BS2

The NM_001267550.2(TTN):​c.76739C>T​(p.Thr25580Met) variant causes a missense change. The variant allele was found at a frequency of 0.00058 in 1,613,318 control chromosomes in the GnomAD database, including 22 homozygotes. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Likely benign (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. T25580A) has been classified as Likely benign.

• Frequency:
  • Genomes: 𝑓 0.00093 (3 hom., cov: 33)
  • Exomes 𝑓: 0.00054 (19 hom.)
• Consequence: TTN NM_001267550.2 missense
• Clinical Significance: Benign/Likely benign criteria provided, multiple submitters, no conflicts B:25
• Conservation: PhyloP100: 6.90
• Publications: 17 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: Benign. The variant received -20 ACMG points.

• BP4: Computational evidence support a benign effect (MetaRNN=0.008473277).
• BP6: Variant 2-178569393-G-A is Benign according to our data. Variant chr2-178569393-G-A is described in ClinVar as Benign/Likely_benign. ClinVar VariationId is 47351.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.
• BS1: Variant frequency is greater than expected in population eas. GnomAd4 allele frequency = 0.000927 (141/152162) while in subpopulation EAS AF = 0.0194 (100/5156). AF 95% confidence interval is 0.0163. There are 3 homozygotes in GnomAd4. There are 73 alleles in the male GnomAd4 subpopulation. Median coverage is 33. This position passed quality control check.
• BS2: High Homozygotes in GnomAd4 at 3 AD,AR gene

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.76739C>T	p.Thr25580Met	missense	Exon 326 of 363	NP_001254479.2
	TTN	NM_001256850.1		c.71816C>T	p.Thr23939Met	missense	Exon 276 of 313	NP_001243779.1
	TTN	NM_133378.4		c.69035C>T	p.Thr23012Met	missense	Exon 275 of 312	NP_596869.4

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	TTN	ENST00000589042.5	TSL:5 MANE Select	c.76739C>T	p.Thr25580Met	missense	Exon 326 of 363	ENSP00000467141.1
	TTN	ENST00000446966.2	TSL:1	c.76583C>T	p.Thr25528Met	missense	Exon 324 of 361	ENSP00000408004.2
	TTN	ENST00000436599.2	TSL:1	c.76463C>T	p.Thr25488Met	missense	Exon 324 of 361	ENSP00000405517.2

Frequencies

GnomAD3 genomes AF: 0.000934 AC: 142 AN: 152044 Hom.: 3 Cov.: 33

Gnomad AFR AF: 0.000531

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.000460

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.0195

Gnomad SAS AF: 0.000207

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.0000882

Gnomad OTH AF: 0.00239

GnomAD2 exomes AF: 0.00166 AC: 413 AN: 248058 AF XY: 0.00152

Gnomad AFR exome AF: 0.000646

Gnomad AMR exome AF: 0.000116

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.0204

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.000178

Gnomad OTH exome AF: 0.00116

GnomAD4 exome AF: 0.000543 AC: 794 AN: 1461156 Hom.: 19 Cov.: 41 AF XY: 0.000530 AC XY: 385 AN XY: 726870

African (AFR) AF: 0.000478 AC: 16 AN: 33438

American (AMR) AF: 0.000268 AC: 12 AN: 44696

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26114

East Asian (EAS) AF: 0.0120 AC: 476 AN: 39646

South Asian (SAS) AF: 0.000290 AC: 25 AN: 86208

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53392

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5758

European-Non Finnish (NFE) AF: 0.0000846 AC: 94 AN: 1111562

Other (OTH) AF: 0.00283 AC: 171 AN: 60342

GnomAD4 genome AF: 0.000927 AC: 141 AN: 152162 Hom.: 3 Cov.: 33 AF XY: 0.000982 AC XY: 73 AN XY: 74366

African (AFR) AF: 0.000530 AC: 22 AN: 41542

American (AMR) AF: 0.000459 AC: 7 AN: 15252

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

East Asian (EAS) AF: 0.0194 AC: 100 AN: 5156

South Asian (SAS) AF: 0.000207 AC: 1 AN: 4832

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10604

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

European-Non Finnish (NFE) AF: 0.0000883 AC: 6 AN: 67988

Other (OTH) AF: 0.00237 AC: 5 AN: 2112

Alfa AF: 0.000376 Hom.: 0

Bravo AF: 0.00128

TwinsUK AF: 0.00 AC: 0

ALSPAC AF: 0.000259 AC: 1

ExAC AF: 0.00166 AC: 201

Asia WGS AF: 0.0130 AC: 44 AN: 3478

EpiCase AF: 0.000218

EpiControl AF: 0.0000593

ClinVar

ClinVar submissions as Germline

Significance: Benign/Likely benign

Revision: criteria provided, multiple submitters, no conflicts

Pathogenic	VUS	Benign	Condition
-	-	7	not specified (7)
-	-	6	not provided (6)
-	-	2	Autosomal recessive limb-girdle muscular dystrophy type 2J (2)
-	-	2	Early-onset myopathy with fatal cardiomyopathy (2)
-	-	2	Myopathy, myofibrillar, 9, with early respiratory failure (2)
-	-	2	Tibial muscular dystrophy (2)
-	-	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)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.079
BayesDel_addAF	Benign	-0.36	T
BayesDel_noAF	Benign	-0.27
CADD	Benign	23
DANN	Benign	0.80
Eigen	Uncertain	0.58
Eigen_PC	Uncertain	0.53
FATHMM_MKL	Uncertain	0.95	D
LIST_S2	Uncertain	0.89	D
MetaRNN	Benign	0.0085	T
MetaSVM	Benign	-0.57	T
MutationAssessor	Uncertain	2.4	M
PhyloP100		6.9
PrimateAI	Uncertain	0.64	T
PROVEAN	Uncertain	-4.1	D
REVEL	Uncertain	0.36
Sift	Uncertain	0.0080	D
Polyphen		1.0	D
Vest4		0.29
MVP		0.40
MPC		0.44
ClinPred		0.042	T
GERP RS		4.8
Mutation Taster		=91/9	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: rs56372592; hg19: chr2-179434120;