2-178529954-A-G

Variant names:

• chr2-178529954-A-G
• rs772189154
• NM_001267550.2:c.106531+6T>C

Variant summary

Our verdict is Likely benign. The variant received -4 ACMG points: 0P and 4B. BP4_Strong

The NM_001267550.2(TTN):​c.106531+6T>C variant causes a splice region, intron change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000029 in 1,584,942 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 3/3 splice prediction tools predict no significant impact on normal splicing. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency:
  • Genomes: 𝑓 0.000033 (0 hom., cov: 33)
  • Exomes 𝑓: 0.000029 (0 hom.)
• Consequence: TTN NM_001267550.2 splice_region, intron
• Scores: Splicing: ADA: 0.02342
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 1.14
• 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: Likely_benign. The variant received -4 ACMG points.

• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.55).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
TTN	NM_001267550.2	c.106531+6T>C		splice_region_variant, intron_variant	Intron 359 of 362	ENST00000589042.5	NP_001254479.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
TTN	ENST00000589042.5	c.106531+6T>C		splice_region_variant, intron_variant	Intron 359 of 362	5	NM_001267550.2	ENSP00000467141.1

Frequencies

GnomAD3 genomes AF: 0.0000328 AC: 5 AN: 152222 Hom.: 0 Cov.: 33

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.0000654

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: 0.0000588

Gnomad OTH AF: 0.00

GnomAD2 exomes AF: 0.0000227 AC: 5 AN: 220592 AF XY: 0.0000249

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.0000795

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.0000633

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.0000190

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.0000286 AC: 41 AN: 1432720 Hom.: 0 Cov.: 32 AF XY: 0.0000281 AC XY: 20 AN XY: 711976

African (AFR) AF: 0.00 AC: 0 AN: 31536

American (AMR) AF: 0.0000568 AC: 2 AN: 35210

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 25098

East Asian (EAS) AF: 0.0000515 AC: 2 AN: 38844

South Asian (SAS) AF: 0.00 AC: 0 AN: 78934

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53280

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5710

European-Non Finnish (NFE) AF: 0.0000290 AC: 32 AN: 1104890

Other (OTH) AF: 0.0000844 AC: 5 AN: 59218

GnomAD4 genome AF: 0.0000328 AC: 5 AN: 152222 Hom.: 0 Cov.: 33 AF XY: 0.00 AC XY: 0 AN XY: 74378

African (AFR) AF: 0.00 AC: 0 AN: 41454

American (AMR) AF: 0.0000654 AC: 1 AN: 15292

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 3472

East Asian (EAS) AF: 0.00 AC: 0 AN: 5202

South Asian (SAS) AF: 0.00 AC: 0 AN: 4834

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10622

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

European-Non Finnish (NFE) AF: 0.0000588 AC: 4 AN: 68026

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

Alfa AF: 0.00 Hom.: 0

Bravo AF: 0.0000189

Asia WGS AF: 0.000289 AC: 1 AN: 3478

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Autosomal recessive limb-girdle muscular dystrophy type 2J;C1858763:Dilated cardiomyopathy 1G Uncertain:1

Mar 15, 2017

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.55
CADD	Benign	15
DANN	Benign	0.91
PhyloP100		1.1
Mutation Taster		=93/7	polymorphism

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Benign	0.023
dbscSNV1_RF	Benign	0.24
SpliceAI score (max)		0.060		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: rs772189154; hg19: chr2-179394681;