rs794729324

Variant names:

• chr2-178607208-GC-G
• rs794729324
• NM_001267550.2:c.53393delG

Variant summary

Our verdict is Pathogenic. The variant received 16 ACMG points: 16P and 0B. PVS1 PP5_Very_Strong

The NM_001267550.2(TTN):​c.53393delG​(p.Gly17798AlafsTer18) variant causes a frameshift change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000434 in 1,612,846 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Likely pathogenic (★★). Synonymous variant affecting the same amino acid position (i.e. G17798G) has been classified as Likely benign. Variant results in nonsense mediated mRNA decay.

• Frequency:
  • Genomes: 𝑓 0.0000066 (0 hom., cov: 33)
  • Exomes 𝑓: 0.0000041 (0 hom.)
• Consequence: TTN NM_001267550.2 frameshift
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:6
• Conservation: PhyloP100: 7.86
• Publications: 5 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: Pathogenic. The variant received 16 ACMG points.

• PVS1: Loss of function variant, product undergoes nonsense mediated mRNA decay. LoF is a known mechanism of disease.
• PP5: Variant 2-178607208-GC-G is Pathogenic according to our data. Variant chr2-178607208-GC-G is described in ClinVar as Pathogenic/Likely_pathogenic. ClinVar VariationId is 202451.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

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

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	TTN	NM_001267550.2	MANE Select	c.53393delG	p.Gly17798AlafsTer18	frameshift	Exon 278 of 363	NP_001254479.2
	TTN	NM_001256850.1		c.48470delG	p.Gly16157AlafsTer18	frameshift	Exon 228 of 313	NP_001243779.1
	TTN	NM_133378.4		c.45689delG	p.Gly15230AlafsTer18	frameshift	Exon 227 of 312	NP_596869.4

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	TTN	ENST00000589042.5	TSL:5 MANE Select	c.53393delG	p.Gly17798AlafsTer18	frameshift	Exon 278 of 363	ENSP00000467141.1
	TTN	ENST00000446966.2	TSL:1	c.53237delG	p.Gly17746AlafsTer18	frameshift	Exon 276 of 361	ENSP00000408004.2
	TTN	ENST00000436599.2	TSL:1	c.53117delG	p.Gly17706AlafsTer18	frameshift	Exon 276 of 361	ENSP00000405517.2

Frequencies

GnomAD3 genomes AF: 0.00000658 AC: 1 AN: 151970 Hom.: 0 Cov.: 33

Gnomad AFR AF: 0.00

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: 0.0000147

Gnomad OTH AF: 0.00

GnomAD4 exome AF: 0.00000411 AC: 6 AN: 1460876 Hom.: 0 Cov.: 31 AF XY: 0.00000275 AC XY: 2 AN XY: 726758

African (AFR) AF: 0.00 AC: 0 AN: 33412

American (AMR) AF: 0.00 AC: 0 AN: 44694

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26100

East Asian (EAS) AF: 0.00 AC: 0 AN: 39608

South Asian (SAS) AF: 0.00 AC: 0 AN: 86226

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

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5754

European-Non Finnish (NFE) AF: 0.00000540 AC: 6 AN: 1111366

Other (OTH) AF: 0.00 AC: 0 AN: 60324

GnomAD4 genome AF: 0.00000658 AC: 1 AN: 151970 Hom.: 0 Cov.: 33 AF XY: 0.0000135 AC XY: 1 AN XY: 74206

African (AFR) AF: 0.00 AC: 0 AN: 41418

American (AMR) AF: 0.00 AC: 0 AN: 15254

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 3468

East Asian (EAS) AF: 0.00 AC: 0 AN: 5132

South Asian (SAS) AF: 0.00 AC: 0 AN: 4826

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10618

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

European-Non Finnish (NFE) AF: 0.0000147 AC: 1 AN: 67936

Other (OTH) AF: 0.00 AC: 0 AN: 2090

Alfa AF: 0.0000712 Hom.: 0

Bravo AF: 0.00000378

ClinVar

ClinVar submissions as Germline

Significance: Pathogenic/Likely pathogenic

Revision: criteria provided, multiple submitters, no conflicts

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

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
PhyloP100		7.9
Mutation Taster		=0/200	disease causing (ClinVar)

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: rs794729324; hg19: chr2-179471935;