rs587782988

Variant names:

• chr2-178595498-TTTAC-T
• rs587782988
• NM_001267550.2:c.57847+5_57847+8delGTAA

Variant summary

Our verdict is Uncertain significance. The variant received 3 ACMG points: 3P and 0B. PM2 PP3

The NM_001267550.2(TTN):​c.57847+5_57847+8delGTAA variant causes a splice region, intron change. The variant allele was found at a frequency of 0.00000215 in 1,393,550 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 Uncertain significance (★★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000022 (0 hom.)
• Consequence: TTN NM_001267550.2 splice_region, intron
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:7
• Conservation: PhyloP100: 6.12
• 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 3 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: Splicing predictors support a deleterious effect. Scorers claiming Pathogenic: max_spliceai. No scorers claiming Uncertain. No scorers claiming Benign.

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.57847+5_57847+8delGTAA		splice_region intron	N/A	NP_001254479.2	Q8WZ42-12
	TTN	NM_001256850.1		c.52924+5_52924+8delGTAA		splice_region intron	N/A	NP_001243779.1	Q8WZ42-1
	TTN	NM_133378.4		c.50143+5_50143+8delGTAA		splice_region 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.57847+5_57847+8delGTAA		splice_region intron	N/A	ENSP00000467141.1	Q8WZ42-12
	TTN	ENST00000446966.2	TSL:1	c.57691+5_57691+8delGTAA		splice_region intron	N/A	ENSP00000408004.2	A0A1B0GXE3
	TTN	ENST00000436599.2	TSL:1	c.57571+5_57571+8delGTAA		splice_region intron	N/A	ENSP00000405517.2	A0A0C4DG59

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD2 exomes AF: 0.00000658 AC: 1 AN: 151874 AF XY: 0.0000125

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: 0.0000169

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000215 AC: 3 AN: 1393550 Hom.: 0 AF XY: 0.00000291 AC XY: 2 AN XY: 687154

⚠️ 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: 30856

American (AMR) AF: 0.00 AC: 0 AN: 34406

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 25150

East Asian (EAS) AF: 0.00 AC: 0 AN: 35762

South Asian (SAS) AF: 0.00 AC: 0 AN: 77212

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 49298

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5662

European-Non Finnish (NFE) AF: 0.00000278 AC: 3 AN: 1077450

Other (OTH) AF: 0.00 AC: 0 AN: 57754

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0.0000000509044), which strongly suggests a high chance of mosaicism in these individuals.

GnomAD4 genome Cov.: 32

Alfa AF: 0.00 Hom.: 0

ClinVar

ClinVar submissions

Significance: Uncertain significance

Revision: criteria provided, multiple submitters, no conflicts

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

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
PhyloP100		6.1
Mutation Taster		=1/99	disease causing

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.67		Details are displayed if max score is > 0.2
DS_DL_spliceai		0.67		Position offset: 9

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: rs587782988;

hg19: chr2-179460225;