2-178669456-A-T

Variant names:

• chr2-178669456-A-T
• rs746940707
• NM_001267550.2:c.35471-9T>A

Variant summary

Our verdict is Uncertain significance. The variant received 4 ACMG points: 4P and 0B. PM2 PP3_Moderate

The NM_001267550.2(TTN):​c.35471-9T>A variant causes a intron change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000323 in 1,546,660 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.

• Frequency:
  • Genomes: 𝑓 0.000020 (0 hom., cov: 32)
  • Exomes 𝑓: 0.0000014 (0 hom.)
• Consequence: TTN NM_001267550.2 intron
• Scores: Splicing: ADA: 0.9997
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: -0.401
• 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 4 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: Splicing predictors support a deleterious effect. Scorers claiming Pathogenic: dbscSNV1_ADA, dbscSNV1_RF, 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

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	TTN	NM_001267550.2	MANE Select	c.35471-9T>A		intron	N/A	NP_001254479.2
	TTN	NM_001256850.1		c.34264+762T>A		intron	N/A	NP_001243779.1
	TTN	NM_133378.4		c.31483+762T>A		intron	N/A	NP_596869.4

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	TTN	ENST00000589042.5	TSL:5 MANE Select	c.35471-9T>A		intron	N/A	ENSP00000467141.1
	TTN	ENST00000446966.2	TSL:1	c.35471-9T>A		intron	N/A	ENSP00000408004.2
	TTN	ENST00000436599.2	TSL:1	c.35195-9T>A		intron	N/A	ENSP00000405517.2

Frequencies

GnomAD3 genomes AF: 0.0000197 AC: 3 AN: 152168 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.0000724

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: 0.00

Gnomad OTH AF: 0.00

GnomAD2 exomes AF: 0.00000568 AC: 1 AN: 176206 AF XY: 0.0000102

Gnomad AFR exome AF: 0.0000849

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: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000143 AC: 2 AN: 1394492 Hom.: 0 Cov.: 29 AF XY: 0.00000289 AC XY: 2 AN XY: 691698

African (AFR) AF: 0.0000658 AC: 2 AN: 30396

American (AMR) AF: 0.00 AC: 0 AN: 33932

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 23702

East Asian (EAS) AF: 0.00 AC: 0 AN: 38108

South Asian (SAS) AF: 0.00 AC: 0 AN: 77252

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 40348

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5510

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 1087404

Other (OTH) AF: 0.00 AC: 0 AN: 57840

GnomAD4 genome AF: 0.0000197 AC: 3 AN: 152168 Hom.: 0 Cov.: 32 AF XY: 0.0000269 AC XY: 2 AN XY: 74322

African (AFR) AF: 0.0000724 AC: 3 AN: 41450

American (AMR) AF: 0.00 AC: 0 AN: 15264

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 3470

East Asian (EAS) AF: 0.00 AC: 0 AN: 5198

South Asian (SAS) AF: 0.00 AC: 0 AN: 4830

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10616

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 316

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 68020

Other (OTH) AF: 0.00 AC: 0 AN: 2092

Alfa AF: 0.00 Hom.: 0

Bravo AF: 0.0000340

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.24
CADD	Benign	23
DANN	Benign	0.86
PhyloP100		-0.40

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.89
SpliceAI score (max)		0.66		Details are displayed if max score is > 0.2
DS_AL_spliceai		0.66		Position offset: -9

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

Other links and lift over

dbSNP: rs746940707; hg19: chr2-179534183;