chr2-178533562-G-A

Variant names:

• chr2-178533562-G-A
• rs3731753
• NM_001267550.2:c.103053C>T

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.103053C>T​(p.Thr34351Thr) variant causes a synonymous change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000305 in 1,613,890 control chromosomes in the GnomAD database, including 3 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 0.00025 (0 hom., cov: 32)
  • Exomes 𝑓: 0.00031 (3 hom.)
• Consequence: TTN NM_001267550.2 synonymous
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:3 B:9
• Conservation: PhyloP100: 0.127
• Publications: 2 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=-0.75).
• BP6: Variant 2-178533562-G-A is Benign according to our data. Variant chr2-178533562-G-A is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 287619.
• BP7: Synonymous conserved (PhyloP=0.127 with no splicing effect.
• BS1: Variant frequency is greater than expected in population eas. GnomAd4 allele frequency = 0.00025 (38/152252) while in subpopulation EAS AF = 0.0054 (28/5184). AF 95% confidence interval is 0.00384. There are 0 homozygotes in GnomAd4. There are 16 alleles in the male GnomAd4 subpopulation. Median coverage is 32. This position passed quality control check.
• BS2: High Homozygotes in GnomAdExome4 at 3 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.103053C>T	p.Thr34351Thr	synonymous	Exon 358 of 363	NP_001254479.2
	TTN	NM_001256850.1		c.98130C>T	p.Thr32710Thr	synonymous	Exon 308 of 313	NP_001243779.1
	TTN	NM_133378.4		c.95349C>T	p.Thr31783Thr	synonymous	Exon 307 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.103053C>T	p.Thr34351Thr	synonymous	Exon 358 of 363	ENSP00000467141.1
	TTN	ENST00000446966.2	TSL:1	c.102897C>T	p.Thr34299Thr	synonymous	Exon 356 of 361	ENSP00000408004.2
	TTN	ENST00000436599.2	TSL:1	c.102777C>T	p.Thr34259Thr	synonymous	Exon 356 of 361	ENSP00000405517.2

Frequencies

GnomAD3 genomes AF: 0.000250 AC: 38 AN: 152134 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.000524

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00539

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.00

Gnomad OTH AF: 0.000955

GnomAD2 exomes AF: 0.000422 AC: 105 AN: 248766 AF XY: 0.000400

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00579

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.000166

GnomAD4 exome AF: 0.000311 AC: 455 AN: 1461638 Hom.: 3 Cov.: 40 AF XY: 0.000329 AC XY: 239 AN XY: 727108

African (AFR) AF: 0.00 AC: 0 AN: 33474

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

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26130

East Asian (EAS) AF: 0.0109 AC: 431 AN: 39698

South Asian (SAS) AF: 0.0000116 AC: 1 AN: 86258

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53378

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5768

European-Non Finnish (NFE) AF: 0.00000450 AC: 5 AN: 1111842

Other (OTH) AF: 0.000298 AC: 18 AN: 60370

GnomAD4 genome AF: 0.000250 AC: 38 AN: 152252 Hom.: 0 Cov.: 32 AF XY: 0.000215 AC XY: 16 AN XY: 74456

African (AFR) AF: 0.00 AC: 0 AN: 41530

American (AMR) AF: 0.000523 AC: 8 AN: 15296

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

East Asian (EAS) AF: 0.00540 AC: 28 AN: 5184

South Asian (SAS) AF: 0.00 AC: 0 AN: 4832

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10608

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

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 68008

Other (OTH) AF: 0.000945 AC: 2 AN: 2116

Alfa AF: 0.000107 Hom.: 0

Bravo AF: 0.000128

Asia WGS AF: 0.00375 AC: 13 AN: 3478

ClinVar

ClinVar submissions as Germline

Significance: Conflicting classifications of pathogenicity

Revision: criteria provided, conflicting classifications

Pathogenic	VUS	Benign	Condition
-	-	4	not specified (4)
-	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	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	not provided (1)
-	-	1	Tibial muscular dystrophy (1)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.75
CADD	Benign	0.031
DANN	Benign	0.58
PhyloP100		0.13
Mutation Taster		=100/0	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: rs3731753; hg19: chr2-179398289;