rs727504851

Variant names:

• chr2-178613158-TA-T
• rs727504851
• NM_001267550.2:c.49648+2delT

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.49648+2delT variant causes a splice donor, intron change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.0000298 in 1,608,536 control chromosomes in the GnomAD database, with no homozygous occurrence. 1/1 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Pathogenic (★★).

• Frequency:
  • Genomes: 𝑓 0.000026 (0 hom., cov: 32)
  • Exomes 𝑓: 0.000030 (0 hom.)
• Consequence: TTN NM_001267550.2 splice_donor, intron
• Clinical Significance: Pathogenic criteria provided, multiple submitters, no conflicts P:16 O:1
• Conservation: PhyloP100: 9.27
• 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: Pathogenic. The variant received 16 ACMG points.

• PVS1: Splicing +-2 bp (donor or acceptor) variant, LoF is a know mechanism of disease, No cryptic splice site detected. Exon removal results in frameshift change.
• PP5: Variant 2-178613158-TA-T is Pathogenic according to our data. Variant chr2-178613158-TA-T is described in ClinVar as Pathogenic. ClinVar VariationId is 179411.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

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	TTN	NM_001267550.2	MANE Select	c.49648+2delT		splice_donor intron	N/A	NP_001254479.2	Q8WZ42-12
	TTN	NM_001256850.1		c.44725+2delT		splice_donor intron	N/A	NP_001243779.1	Q8WZ42-1
	TTN	NM_133378.4		c.41944+2delT		splice_donor intron	N/A	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.49648+2delT		splice_donor intron	N/A	ENSP00000467141.1	Q8WZ42-12
	TTN	ENST00000446966.2	TSL:1	c.49492+2delT		splice_donor intron	N/A	ENSP00000408004.2	A0A1B0GXE3
	TTN	ENST00000436599.2	TSL:1	c.49372+2delT		splice_donor intron	N/A	ENSP00000405517.2	A0A0C4DG59

Frequencies

GnomAD3 genomes AF: 0.0000263 AC: 4 AN: 151928 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: 0.00

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.0000589

Gnomad OTH AF: 0.00

GnomAD2 exomes AF: 0.0000164 AC: 4 AN: 244206 AF XY: 0.00000755

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.0000270

Gnomad OTH exome AF: 0.000169

GnomAD4 exome AF: 0.0000302 AC: 44 AN: 1456608 Hom.: 0 Cov.: 33 AF XY: 0.0000235 AC XY: 17 AN XY: 724510

African (AFR) AF: 0.00 AC: 0 AN: 33032

American (AMR) AF: 0.00 AC: 0 AN: 43894

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26054

East Asian (EAS) AF: 0.00 AC: 0 AN: 39386

South Asian (SAS) AF: 0.00 AC: 0 AN: 85014

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53288

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5748

European-Non Finnish (NFE) AF: 0.0000324 AC: 36 AN: 1110086

Other (OTH) AF: 0.000133 AC: 8 AN: 60106

GnomAD4 genome AF: 0.0000263 AC: 4 AN: 151928 Hom.: 0 Cov.: 32 AF XY: 0.0000404 AC XY: 3 AN XY: 74198

African (AFR) AF: 0.00 AC: 0 AN: 41408

American (AMR) AF: 0.00 AC: 0 AN: 15234

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 3466

East Asian (EAS) AF: 0.00 AC: 0 AN: 5138

South Asian (SAS) AF: 0.00 AC: 0 AN: 4832

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: 0.0000589 AC: 4 AN: 67924

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

Alfa AF: 0.000142 Hom.: 0

Bravo AF: 0.0000189

ClinVar

ClinVar submissions

Significance: Pathogenic

Revision: criteria provided, multiple submitters, no conflicts

Pathogenic	VUS	Benign	Condition
6	-	-	not provided (6)
2	-	-	Cardiomyopathy (2)
2	-	-	Cardiovascular phenotype (2)
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	-	-	Dilated cardiomyopathy 1G (1)
1	-	-	Primary dilated cardiomyopathy (1)
1	-	-	Tibial muscular dystrophy (1)
1	-	-	TTN-related disorder (1)
-	-	-	Primary dilated cardiomyopathy;C1837342:Autosomal recessive limb-girdle muscular dystrophy type 2J;C1838244:Tibial muscular dystrophy;C1863599:Myopathy, myofibrillar, 9, with early respiratory failure (1)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
PhyloP100		9.3
Mutation Taster		=0/100	disease causing (ClinVar)

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.81		Details are displayed if max score is > 0.2
DS_DL_spliceai		0.81		Position offset: 3

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Other links and lift over

dbSNP: rs727504851; hg19: chr2-179477885;