NM_001267550.2:c.70677T>C

Variant names:

• chr2-178575455-A-G
• rs72646890
• NM_001267550.2:c.70677T>C

Variant summary

Our verdict is Benign. The variant received -14 ACMG points: 0P and 14B. BP4_Strong BP6 BP7 BS1 BS2

The NM_001267550.2(TTN):​c.70677T>C​(p.Asp23559Asp) variant causes a synonymous change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00378 in 1,613,530 control chromosomes in the GnomAD database, including 19 homozygotes. 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 0.0025 (1 hom., cov: 32)
  • Exomes 𝑓: 0.0039 (18 hom.)
• Consequence: TTN NM_001267550.2 synonymous
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:3 B:19
• Conservation: PhyloP100: 0.131
• 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: Benign. The variant received -14 ACMG points.

• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.53).
• BP6: Variant 2-178575455-A-G is Benign according to our data. Variant chr2-178575455-A-G is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 47289.
• BP7: Synonymous conserved (PhyloP=0.131 with no splicing effect.
• BS1: Variant frequency is greater than expected in population nfe. GnomAd4 allele frequency = 0.0025 (380/152162) while in subpopulation NFE AF = 0.00471 (320/67984). AF 95% confidence interval is 0.00428. There are 1 homozygotes in GnomAd4. There are 160 alleles in the male GnomAd4 subpopulation. Median coverage is 32. This position passed quality control check.
• BS2: High Homozygotes in GnomAdExome4 at 18 AD,AR gene

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.70677T>C	p.Asp23559Asp	synonymous	Exon 326 of 363	NP_001254479.2
	TTN	NM_001256850.1		c.65754T>C	p.Asp21918Asp	synonymous	Exon 276 of 313	NP_001243779.1
	TTN	NM_133378.4		c.62973T>C	p.Asp20991Asp	synonymous	Exon 275 of 312	NP_596869.4

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	TTN	ENST00000589042.5	TSL:5 MANE Select	c.70677T>C	p.Asp23559Asp	synonymous	Exon 326 of 363	ENSP00000467141.1
	TTN	ENST00000446966.2	TSL:1	c.70521T>C	p.Asp23507Asp	synonymous	Exon 324 of 361	ENSP00000408004.2
	TTN	ENST00000436599.2	TSL:1	c.70401T>C	p.Asp23467Asp	synonymous	Exon 324 of 361	ENSP00000405517.2

Frequencies

GnomAD3 genomes AF: 0.00250 AC: 380 AN: 152044 Hom.: 1 Cov.: 32

Gnomad AFR AF: 0.000579

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00144

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00145

Gnomad FIN AF: 0.000377

Gnomad MID AF: 0.00316

Gnomad NFE AF: 0.00471

Gnomad OTH AF: 0.000956

GnomAD2 exomes AF: 0.00244 AC: 606 AN: 248240 AF XY: 0.00261

Gnomad AFR exome AF: 0.000323

Gnomad AMR exome AF: 0.00107

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad FIN exome AF: 0.000232

Gnomad NFE exome AF: 0.00439

Gnomad OTH exome AF: 0.00366

GnomAD4 exome AF: 0.00392 AC: 5724 AN: 1461368 Hom.: 18 Cov.: 36 AF XY: 0.00375 AC XY: 2724 AN XY: 726964

African (AFR) AF: 0.000628 AC: 21 AN: 33464

American (AMR) AF: 0.00116 AC: 52 AN: 44720

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26124

East Asian (EAS) AF: 0.00 AC: 0 AN: 39662

South Asian (SAS) AF: 0.00187 AC: 161 AN: 86248

European-Finnish (FIN) AF: 0.000487 AC: 26 AN: 53394

Middle Eastern (MID) AF: 0.00139 AC: 8 AN: 5760

European-Non Finnish (NFE) AF: 0.00468 AC: 5204 AN: 1111638

Other (OTH) AF: 0.00418 AC: 252 AN: 60358

GnomAD4 genome AF: 0.00250 AC: 380 AN: 152162 Hom.: 1 Cov.: 32 AF XY: 0.00215 AC XY: 160 AN XY: 74368

African (AFR) AF: 0.000578 AC: 24 AN: 41540

American (AMR) AF: 0.00144 AC: 22 AN: 15276

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 3466

East Asian (EAS) AF: 0.00 AC: 0 AN: 5162

South Asian (SAS) AF: 0.00145 AC: 7 AN: 4812

European-Finnish (FIN) AF: 0.000377 AC: 4 AN: 10604

Middle Eastern (MID) AF: 0.00340 AC: 1 AN: 294

European-Non Finnish (NFE) AF: 0.00471 AC: 320 AN: 67984

Other (OTH) AF: 0.000946 AC: 2 AN: 2114

Alfa AF: 0.00402 Hom.: 2

Bravo AF: 0.00233

Asia WGS AF: 0.000577 AC: 2 AN: 3478

ClinVar

ClinVar submissions as Germline

Significance: Conflicting classifications of pathogenicity

Revision: criteria provided, conflicting classifications

Pathogenic	VUS	Benign	Condition
-	-	7	not specified (7)
-	-	6	not provided (6)
-	1	-	Autosomal recessive limb-girdle muscular dystrophy type 2J (1)
-	-	1	Autosomal recessive limb-girdle muscular dystrophy type 2J;C1858763:Dilated cardiomyopathy 1G (1)
-	-	1	Cardiomyopathy (1)
-	-	1	Cardiovascular phenotype (1)
-	1	-	Dilated cardiomyopathy 1G (1)
-	1	-	Early-onset myopathy with fatal cardiomyopathy (1)
-	-	1	Myopathy, myofibrillar, 9, with early respiratory failure (1)
-	-	1	Tibial muscular dystrophy (1)
-	-	1	TTN-related disorder (1)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.53
CADD	Benign	0.030
DANN	Benign	0.67
PhyloP100		0.13
Mutation Taster		=65/35	polymorphism

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: rs72646890; hg19: chr2-179440182;