chr2-178749916-G-A

Variant names:

• chr2-178749916-G-A
• rs727504521
• NM_001267550.2:c.11311+3208C>T

Variant summary

Our verdict is Uncertain significance. The variant received 4 ACMG points: 4P and 0B. PVS1_Strong

The NM_133379.5(TTN):​c.12484C>T​(p.Gln4162*) variant causes a stop gained change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000821 in 1,461,088 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 Uncertain significance (★★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000082 (0 hom.)
• Consequence: TTN NM_133379.5 stop_gained
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:3
• Conservation: PhyloP100: 1.41
• Publications: 0 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 0.258 CDS is truncated, and there are 2 pathogenic variants in the truncated region.

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

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	TTN	NM_001267550.2	MANE Select	c.11311+3208C>T		intron	N/A	NP_001254479.2
	TTN	NM_133379.5		c.12484C>T	p.Gln4162*	stop_gained	Exon 46 of 46	NP_596870.2
	TTN	NM_001256850.1		c.10360+3208C>T		intron	N/A	NP_001243779.1

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	TTN	ENST00000589042.5	TSL:5 MANE Select	c.11311+3208C>T		intron	N/A	ENSP00000467141.1
	TTN	ENST00000446966.2	TSL:1	c.11311+3208C>T		intron	N/A	ENSP00000408004.2
	TTN	ENST00000436599.2	TSL:1	c.11035+3208C>T		intron	N/A	ENSP00000405517.2

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD2 exomes AF: 0.00000802 AC: 2 AN: 249256 AF XY: 0.0000148

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: 0.0000178

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000821 AC: 12 AN: 1461088 Hom.: 0 Cov.: 36 AF XY: 0.0000110 AC XY: 8 AN XY: 726860

African (AFR) AF: 0.00 AC: 0 AN: 33444

American (AMR) AF: 0.00 AC: 0 AN: 44612

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

East Asian (EAS) AF: 0.00 AC: 0 AN: 39634

South Asian (SAS) AF: 0.00 AC: 0 AN: 86242

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53382

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5764

European-Non Finnish (NFE) AF: 0.0000108 AC: 12 AN: 1111568

Other (OTH) AF: 0.00 AC: 0 AN: 60342

GnomAD4 genome Cov.: 32

Alfa AF: 0.00 Hom.: 0

Bravo AF: 0.00000756

ExAC AF: 0.0000165 AC: 2

EpiCase AF: 0.00

EpiControl AF: 0.0000593

ClinVar

ClinVar submissions as Germline

Significance: Uncertain significance

Revision: criteria provided, multiple submitters, no conflicts

Pathogenic	VUS	Benign	Condition
-	1	-	Cardiovascular phenotype (1)
-	1	-	not provided (1)
-	1	-	not specified (1)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Benign	-0.23	T
BayesDel_noAF	Benign	-0.55
CADD	Benign	17
DANN	Uncertain	0.99
Eigen	Benign	-0.16
Eigen_PC	Benign	-0.12
FATHMM_MKL	Benign	0.21	N
PhyloP100		1.4
Vest4		0.35
GERP RS		3.9
Mutation Taster		=20/180	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: rs727504521; hg19: chr2-179614643;