2-178746953-G-C

Variant names:

• chr2-178746953-G-C
• rs72648911
• NM_001267550.2:c.11312-5032C>G

Variant summary

Our verdict is Uncertain significance. The variant received 4 ACMG points: 4P and 0B. PVS1_Moderate PM2

The NM_133379.5(TTN):​c.15447C>G​(p.Tyr5149*) variant causes a stop gained change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000137 in 1,461,442 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar. Synonymous variant affecting the same amino acid position (i.e. Y5149Y) has been classified as Benign.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000014 (0 hom.)
• Consequence: TTN NM_133379.5 stop_gained
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: -0.104
• Publications: 4 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: Uncertain_significance. The variant received 4 ACMG points.

• PVS1: Loss of function variant, product does not undergo nonsense mediated mRNA decay. Variant is located in the 3'-most exon, not predicted to undergo nonsense mediated mRNA decay. Fraction of 0.0814 CDS is truncated, and there are 1 pathogenic variants in the truncated region.
• PM2: Very rare variant in population databases, with high coverage

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_133379.5. 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.11312-5032C>G		intron	N/A	NP_001254479.2	Q8WZ42-12
	TTN	NM_133379.5		c.15447C>G	p.Tyr5149*	stop_gained	Exon 46 of 46	NP_596870.2	Q8WZ42-6
	TTN	NM_001256850.1		c.10361-5032C>G		intron	N/A	NP_001243779.1	Q8WZ42-1

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	TTN	ENST00000589042.5	TSL:5 MANE Select	c.11312-5032C>G		intron	N/A	ENSP00000467141.1	Q8WZ42-12
	TTN	ENST00000446966.2	TSL:1	c.11312-5032C>G		intron	N/A	ENSP00000408004.2	A0A1B0GXE3
	TTN	ENST00000436599.2	TSL:1	c.11036-5032C>G		intron	N/A	ENSP00000405517.2	A0A0C4DG59

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD2 exomes AF: 0.00000399 AC: 1 AN: 250840 AF XY: 0.00000738

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: 0.00000883

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000137 AC: 2 AN: 1461442 Hom.: 0 Cov.: 33 AF XY: 0.00000275 AC XY: 2 AN XY: 727020

African (AFR) AF: 0.00 AC: 0 AN: 33446

American (AMR) AF: 0.00 AC: 0 AN: 44698

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26112

East Asian (EAS) AF: 0.00 AC: 0 AN: 39674

South Asian (SAS) AF: 0.00 AC: 0 AN: 86254

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53416

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

European-Non Finnish (NFE) AF: 0.00000180 AC: 2 AN: 1111708

Other (OTH) AF: 0.00 AC: 0 AN: 60372

GnomAD4 genome Cov.: 32

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Benign	-0.30	T
BayesDel_noAF	Benign	-0.67
CADD	Benign	0.16
DANN	Benign	0.89
Eigen	Benign	-1.1
Eigen_PC	Benign	-1.2
FATHMM_MKL	Benign	0.19	N
PhyloP100		-0.10
Vest4		0.31
GERP RS		-2.6
Mutation Taster		=50/150	disease causing

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: rs72648911; hg19: chr2-179611680;