rs75948012

Variant names:

• chr2-178576076-T-C
• rs75948012
• NM_001267550.2:c.70056A>G

Variant summary

Our verdict is Likely benign. The variant received -6 ACMG points: 0P and 6B. BP4_Strong BP6 BP7

The NM_001267550.2(TTN):​c.70056A>G​(p.Arg23352Arg) variant causes a synonymous change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000366 in 1,613,542 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 Conflicting classifications of pathogenicity (no stars).

• Frequency:
  • Genomes: 𝑓 0.00024 (0 hom., cov: 32)
  • Exomes 𝑓: 0.000016 (0 hom.)
• Consequence: TTN NM_001267550.2 synonymous
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:1 B:4
• Conservation: PhyloP100: 2.29
• Publications: 1 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 -6 ACMG points.

• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.48).
• BP6: Variant 2-178576076-T-C is Benign according to our data. Variant chr2-178576076-T-C is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 178193.
• BP7: Synonymous conserved (PhyloP=2.29 with no splicing effect.

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.70056A>G	p.Arg23352Arg	synonymous	Exon 326 of 363	NP_001254479.2	Q8WZ42-12
	TTN	NM_001256850.1		c.65133A>G	p.Arg21711Arg	synonymous	Exon 276 of 313	NP_001243779.1	Q8WZ42-1
	TTN	NM_133378.4		c.62352A>G	p.Arg20784Arg	synonymous	Exon 275 of 312	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.70056A>G	p.Arg23352Arg	synonymous	Exon 326 of 363	ENSP00000467141.1	Q8WZ42-12
	TTN	ENST00000446966.2	TSL:1	c.69900A>G	p.Arg23300Arg	synonymous	Exon 324 of 361	ENSP00000408004.2	A0A1B0GXE3
	TTN	ENST00000436599.2	TSL:1	c.69780A>G	p.Arg23260Arg	synonymous	Exon 324 of 361	ENSP00000405517.2	A0A0C4DG59

Frequencies

GnomAD3 genomes AF: 0.000237 AC: 36 AN: 152098 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.000869

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: 0.0000563 AC: 14 AN: 248568 AF XY: 0.0000297

Gnomad AFR exome AF: 0.000905

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: 0.0000157 AC: 23 AN: 1461326 Hom.: 0 Cov.: 36 AF XY: 0.00000963 AC XY: 7 AN XY: 726946

African (AFR) AF: 0.000628 AC: 21 AN: 33452

American (AMR) AF: 0.00 AC: 0 AN: 44720

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26126

East Asian (EAS) AF: 0.00 AC: 0 AN: 39648

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

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53392

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5760

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 1111630

Other (OTH) AF: 0.0000331 AC: 2 AN: 60356

GnomAD4 genome AF: 0.000237 AC: 36 AN: 152216 Hom.: 0 Cov.: 32 AF XY: 0.000228 AC XY: 17 AN XY: 74422

African (AFR) AF: 0.000866 AC: 36 AN: 41566

American (AMR) AF: 0.00 AC: 0 AN: 15282

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

East Asian (EAS) AF: 0.00 AC: 0 AN: 5152

South Asian (SAS) AF: 0.00 AC: 0 AN: 4822

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

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 294

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 67982

Other (OTH) AF: 0.00 AC: 0 AN: 2114

Alfa AF: 0.000109 Hom.: 0

Bravo AF: 0.000230

ClinVar

ClinVar submissions

Significance: Conflicting classifications of pathogenicity

Revision: criteria provided, conflicting classifications

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

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.48
CADD	Benign	1.2
DANN	Benign	0.80
PhyloP100		2.3
Mutation Taster		=23/77	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: rs75948012; hg19: chr2-179440803;