2-178735662-G-T

Variant names:

• chr2-178735662-G-T
• rs373875040
• NM_001267550.2:c.14784C>A

Variant summary

Our verdict is Benign. The variant received -17 ACMG points: 0P and 17B. BP4_Strong BP6_Very_Strong BP7 BS1

The NM_001267550.2(TTN):​c.14784C>A​(p.Leu4928Leu) variant causes a synonymous change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000154 in 1,613,746 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 Likely benign (★★). Synonymous variant affecting the same amino acid position (i.e. L4928L) has been classified as Likely benign.

• Frequency:
  • Genomes: 𝑓 0.00083 (0 hom., cov: 33)
  • Exomes 𝑓: 0.000083 (0 hom.)
• Consequence: TTN NM_001267550.2 synonymous
• Clinical Significance: Benign/Likely benign criteria provided, multiple submitters, no conflicts B:12
• Conservation: PhyloP100: -1.07
• Publications: 2 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 -17 ACMG points.

• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.81).
• BP6: Variant 2-178735662-G-T is Benign according to our data. Variant chr2-178735662-G-T is described in ClinVar as Benign/Likely_benign. ClinVar VariationId is 46593.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.
• BP7: Synonymous conserved (PhyloP=-1.07 with no splicing effect.
• BS1: Variant frequency is greater than expected in population afr. GnomAd4 allele frequency = 0.000827 (126/152272) while in subpopulation AFR AF = 0.00294 (122/41560). AF 95% confidence interval is 0.00251. There are 0 homozygotes in GnomAd4. There are 63 alleles in the male GnomAd4 subpopulation. Median coverage is 33. This position passed quality control check.

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.14784C>A	p.Leu4928Leu	synonymous	Exon 50 of 363	NP_001254479.2	Q8WZ42-12
	TTN	NM_001256850.1		c.13833C>A	p.Leu4611Leu	synonymous	Exon 48 of 313	NP_001243779.1	Q8WZ42-1
	TTN	NM_133378.4		c.11052C>A	p.Leu3684Leu	synonymous	Exon 47 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.14784C>A	p.Leu4928Leu	synonymous	Exon 50 of 363	ENSP00000467141.1	Q8WZ42-12
	TTN	ENST00000446966.2	TSL:1	c.14784C>A	p.Leu4928Leu	synonymous	Exon 50 of 361	ENSP00000408004.2	A0A1B0GXE3
	TTN	ENST00000436599.2	TSL:1	c.14508C>A	p.Leu4836Leu	synonymous	Exon 48 of 361	ENSP00000405517.2	A0A0C4DG59

Frequencies

GnomAD3 genomes AF: 0.000802 AC: 122 AN: 152154 Hom.: 0 Cov.: 33

Gnomad AFR AF: 0.00285

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.000131

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: 0.0000147

Gnomad OTH AF: 0.000479

GnomAD2 exomes AF: 0.000257 AC: 64 AN: 248582 AF XY: 0.000208

Gnomad AFR exome AF: 0.00388

Gnomad AMR exome AF: 0.0000580

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00000888

Gnomad OTH exome AF: 0.000166

GnomAD4 exome AF: 0.0000835 AC: 122 AN: 1461474 Hom.: 0 Cov.: 29 AF XY: 0.0000619 AC XY: 45 AN XY: 727006

African (AFR) AF: 0.00248 AC: 83 AN: 33472

American (AMR) AF: 0.000112 AC: 5 AN: 44716

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26132

East Asian (EAS) AF: 0.00 AC: 0 AN: 39648

South Asian (SAS) AF: 0.00 AC: 0 AN: 86248

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53350

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5762

European-Non Finnish (NFE) AF: 0.0000180 AC: 20 AN: 1111788

Other (OTH) AF: 0.000232 AC: 14 AN: 60358

GnomAD4 genome AF: 0.000827 AC: 126 AN: 152272 Hom.: 0 Cov.: 33 AF XY: 0.000846 AC XY: 63 AN XY: 74454

African (AFR) AF: 0.00294 AC: 122 AN: 41560

American (AMR) AF: 0.000131 AC: 2 AN: 15290

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

East Asian (EAS) AF: 0.00 AC: 0 AN: 5176

South Asian (SAS) AF: 0.00 AC: 0 AN: 4822

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: 0.0000147 AC: 1 AN: 68014

Other (OTH) AF: 0.000474 AC: 1 AN: 2110

Alfa AF: 0.000278 Hom.: 0

Bravo AF: 0.000994

Asia WGS AF: 0.000867 AC: 3 AN: 3476

ClinVar

ClinVar submissions

Significance: Benign/Likely benign

Revision: criteria provided, multiple submitters, no conflicts

Pathogenic	VUS	Benign	Condition
-	-	6	not specified (6)
-	-	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	Early-onset myopathy with fatal cardiomyopathy (1)
-	-	1	Myopathy, myofibrillar, 9, with early respiratory failure (1)
-	-	1	not provided (1)
-	-	1	Tibial muscular dystrophy (1)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.81
CADD	Benign	0.091
DANN	Benign	0.58
PhyloP100		-1.1
Mutation Taster		=90/10	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: rs373875040; hg19: chr2-179600389; COSMIC: COSV60146563; COSMIC: COSV60146563;