rs1486772794

Variant names:

• chr2-178653702-CT-C
• rs1486772794
• NM_001267550.2:c.38546-2delA

Variant summary

Our verdict is Uncertain significance. The variant received 2 ACMG points: 2P and 0B. PVS1_Moderate

The NM_001267550.2(TTN):​c.38546-2delA variant causes a splice acceptor, intron change. 1/1 splice prediction tools predict no significant impact on normal splicing. Variant has been reported in ClinVar as Uncertain significance (★★).

• Frequency:
  • Genomes: 𝑓 0.000031 (0 hom., cov: 19)
  • Exomes 𝑓: 0.000012 (0 hom.)
  • Failed GnomAD Quality Control
• Consequence: TTN NM_001267550.2 splice_acceptor, intron
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: 3.69
• 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]

LOC124906100 (HGNC:):

ACMG classification

Our verdict: Uncertain_significance. The variant received 2 ACMG points.

• PVS1: Splicing +-2 bp (donor or acceptor) variant, product NOT destroyed by NMD, known LOF gene, truncates exone, which is 7.501667E-4 fraction of the gene. Cryptic splice site detected, with MaxEntScore 6.7, offset of 0 (no position change), new splice context is: aaactactaatatctttcAGtgc. Cryptic site results in inframe change. If cryptic site found is not functional and variant results in exon loss, it results in inframe change.

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.38546-2delA		splice_acceptor intron	N/A	NP_001254479.2	Q8WZ42-12
	TTN	NM_001256850.1		c.34523-1162delA		intron	N/A	NP_001243779.1	Q8WZ42-1
	TTN	NM_133378.4		c.31742-1162delA		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.38546-2delA		splice_acceptor intron	N/A	ENSP00000467141.1	Q8WZ42-12
	TTN	ENST00000446966.2	TSL:1	c.38546-2delA		splice_acceptor intron	N/A	ENSP00000408004.2	A0A1B0GXE3
	TTN	ENST00000436599.2	TSL:1	c.38270-2delA		splice_acceptor intron	N/A	ENSP00000405517.2	A0A0C4DG59

Frequencies

GnomAD3 genomes AF: 0.0000314 AC: 4 AN: 127404 Hom.: 0 Cov.: 19

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.000874

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.00

Gnomad OTH AF: 0.00

GnomAD2 exomes AF: 0.000103 AC: 4 AN: 38682 AF XY: 0.0000503

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.000644

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome Data not reliable, filtered out with message: AS_VQSR AF: 0.0000121 AC: 11 AN: 908950 Hom.: 0 Cov.: 12 AF XY: 0.00000871 AC XY: 4 AN XY: 459060

⚠️ The allele balance in gnomAD version 4 Exomes is significantly skewed from the expected value of 0.5.

African (AFR) AF: 0.00 AC: 0 AN: 22636

American (AMR) AF: 0.00 AC: 0 AN: 22690

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 18110

East Asian (EAS) AF: 0.000295 AC: 10 AN: 33878

South Asian (SAS) AF: 0.00 AC: 0 AN: 61794

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 31268

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 2966

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 673954

Other (OTH) AF: 0.0000240 AC: 1 AN: 41654

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0.000000237303), which strongly suggests a high chance of mosaicism in these individuals.

GnomAD4 genome AF: 0.0000314 AC: 4 AN: 127496 Hom.: 0 Cov.: 19 AF XY: 0.0000659 AC XY: 4 AN XY: 60660

⚠️ The allele balance in gnomAD version 4 Genomes is significantly skewed from the expected value of 0.5.

African (AFR) AF: 0.00 AC: 0 AN: 34836

American (AMR) AF: 0.00 AC: 0 AN: 11938

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 3138

East Asian (EAS) AF: 0.000877 AC: 4 AN: 4562

South Asian (SAS) AF: 0.00 AC: 0 AN: 3790

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 6860

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 260

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 59618

Other (OTH) AF: 0.00 AC: 0 AN: 1618

⚠️ The allele balance in gnomAD version 4 Genomes is significantly skewed from the expected value of 0.5. (p-value = 0.00921106), which strongly suggests a high chance of mosaicism in these individuals.

Alfa AF: 0.00 Hom.: 0

Bravo AF: 0.0000227

ClinVar

ClinVar submissions

Significance: Uncertain significance

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	-	not provided (1)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
PhyloP100		3.7
Mutation Taster		=8/92	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

MaxEntScan Visualizer can be used to analyze the impact of this mutation on the neighboring sequence.

Other links and lift over

dbSNP: rs1486772794;

hg19: chr2-179518429;