rs76928874

Variant names:

• chr2-178560080-A-G
• rs76928874
• NM_001267550.2:c.86052T>C

Variant summary

Our verdict is Benign. The variant received -10 ACMG points: 0P and 10B. BP4_Strong BP6 BP7 BS1

The NM_001267550.2(TTN):​c.86052T>C​(p.Thr28684Thr) variant causes a synonymous change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00021 in 1,613,656 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 0.00031 (0 hom., cov: 33)
  • Exomes 𝑓: 0.00020 (0 hom.)
• Consequence: TTN NM_001267550.2 synonymous
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:3 B:12
• Conservation: PhyloP100: 0.0180
• 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 -10 ACMG points.

• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.5).
• BP6: Variant 2-178560080-A-G is Benign according to our data. Variant chr2-178560080-A-G is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 196076.
• BP7: Synonymous conserved (PhyloP=0.018 with no splicing effect.
• BS1: Variant frequency is greater than expected in population eas. GnomAd4 allele frequency = 0.000309 (47/152184) while in subpopulation EAS AF = 0.00736 (38/5160). AF 95% confidence interval is 0.00551. There are 0 homozygotes in GnomAd4. There are 31 alleles in the male GnomAd4 subpopulation. Median coverage is 33. This position passed quality control check.

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.86052T>C	p.Thr28684Thr	synonymous	Exon 326 of 363	NP_001254479.2
	TTN	NM_001256850.1		c.81129T>C	p.Thr27043Thr	synonymous	Exon 276 of 313	NP_001243779.1
	TTN	NM_133378.4		c.78348T>C	p.Thr26116Thr	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.86052T>C	p.Thr28684Thr	synonymous	Exon 326 of 363	ENSP00000467141.1
	TTN	ENST00000446966.2	TSL:1	c.85896T>C	p.Thr28632Thr	synonymous	Exon 324 of 361	ENSP00000408004.2
	TTN	ENST00000436599.2	TSL:1	c.85776T>C	p.Thr28592Thr	synonymous	Exon 324 of 361	ENSP00000405517.2

Frequencies

GnomAD3 genomes AF: 0.000309 AC: 47 AN: 152066 Hom.: 0 Cov.: 33

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.0000656

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00735

Gnomad SAS AF: 0.00145

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.0000147

Gnomad OTH AF: 0.00

GnomAD2 exomes AF: 0.000586 AC: 145 AN: 247422 AF XY: 0.000581

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00716

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.000333

GnomAD4 exome AF: 0.000200 AC: 292 AN: 1461472 Hom.: 0 Cov.: 32 AF XY: 0.000202 AC XY: 147 AN XY: 727020

African (AFR) AF: 0.00 AC: 0 AN: 33472

American (AMR) AF: 0.0000224 AC: 1 AN: 44722

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26128

East Asian (EAS) AF: 0.00550 AC: 218 AN: 39644

South Asian (SAS) AF: 0.000510 AC: 44 AN: 86252

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53350

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5764

European-Non Finnish (NFE) AF: 0.00000360 AC: 4 AN: 1111776

Other (OTH) AF: 0.000414 AC: 25 AN: 60364

GnomAD4 genome AF: 0.000309 AC: 47 AN: 152184 Hom.: 0 Cov.: 33 AF XY: 0.000417 AC XY: 31 AN XY: 74374

African (AFR) AF: 0.00 AC: 0 AN: 41532

American (AMR) AF: 0.0000655 AC: 1 AN: 15270

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

East Asian (EAS) AF: 0.00736 AC: 38 AN: 5160

South Asian (SAS) AF: 0.00145 AC: 7 AN: 4828

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10602

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

European-Non Finnish (NFE) AF: 0.0000147 AC: 1 AN: 68006

Other (OTH) AF: 0.00 AC: 0 AN: 2108

Alfa AF: 0.00 Hom.: 0

Bravo AF: 0.000234

Asia WGS AF: 0.00520 AC: 18 AN: 3478

ClinVar

ClinVar submissions as Germline

Significance: Conflicting classifications of pathogenicity

Revision: criteria provided, conflicting classifications

Pathogenic	VUS	Benign	Condition
-	-	5	not specified (5)
-	-	3	not provided (3)
-	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	Tibial muscular dystrophy (1)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.50
CADD	Benign	0.015
DANN	Benign	0.69
PhyloP100		0.018
Mutation Taster		=80/20	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: rs76928874; hg19: chr2-179424807;