NM_001267550.2:c.20792A>G

Variant names:

• chr2-178725412-T-C
• rs200866883
• NM_001267550.2:c.20792A>G

Variant summary

Our verdict is Likely benign. The variant received -3 ACMG points: 0P and 3B. BP4_Moderate BP6

The NM_001267550.2(TTN):​c.20792A>G​(p.Asn6931Ser) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.000339 in 1,606,838 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 0.00025 (0 hom., cov: 33)
  • Exomes 𝑓: 0.00035 (0 hom.)
• Consequence: TTN NM_001267550.2 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:7 B:7
• Conservation: PhyloP100: 7.67
• 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]

ENSG00000267784 (HGNC:):

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 -3 ACMG points.

• BP4: Computational evidence support a benign effect (MetaRNN=0.15661943).
• BP6: Variant 2-178725412-T-C is Benign according to our data. Variant chr2-178725412-T-C is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 282786.

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

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	TTN	NM_001267550.2	MANE Select	c.20792A>G	p.Asn6931Ser	missense	Exon 71 of 363	NP_001254479.2
	TTN	NM_001256850.1		c.19841A>G	p.Asn6614Ser	missense	Exon 69 of 313	NP_001243779.1
	TTN	NM_133378.4		c.17060A>G	p.Asn5687Ser	missense	Exon 68 of 312	NP_596869.4

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	TTN	ENST00000589042.5	TSL:5 MANE Select	c.20792A>G	p.Asn6931Ser	missense	Exon 71 of 363	ENSP00000467141.1
	TTN	ENST00000446966.2	TSL:1	c.20792A>G	p.Asn6931Ser	missense	Exon 71 of 361	ENSP00000408004.2
	TTN	ENST00000436599.2	TSL:1	c.20516A>G	p.Asn6839Ser	missense	Exon 69 of 361	ENSP00000405517.2

Frequencies

GnomAD3 genomes AF: 0.000250 AC: 38 AN: 152202 Hom.: 0 Cov.: 33

Gnomad AFR AF: 0.000121

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.0000655

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: 0.000470

Gnomad OTH AF: 0.00

GnomAD2 exomes AF: 0.000206 AC: 50 AN: 242304 AF XY: 0.000228

Gnomad AFR exome AF: 0.0000654

Gnomad AMR exome AF: 0.0000589

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.000420

Gnomad OTH exome AF: 0.000171

GnomAD4 exome AF: 0.000348 AC: 506 AN: 1454518 Hom.: 0 Cov.: 30 AF XY: 0.000338 AC XY: 244 AN XY: 722758

African (AFR) AF: 0.000120 AC: 4 AN: 33354

American (AMR) AF: 0.0000452 AC: 2 AN: 44288

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 25770

East Asian (EAS) AF: 0.00 AC: 0 AN: 39478

South Asian (SAS) AF: 0.00 AC: 0 AN: 85000

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 52968

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5744

European-Non Finnish (NFE) AF: 0.000432 AC: 479 AN: 1107848

Other (OTH) AF: 0.000350 AC: 21 AN: 60068

GnomAD4 genome AF: 0.000249 AC: 38 AN: 152320 Hom.: 0 Cov.: 33 AF XY: 0.000242 AC XY: 18 AN XY: 74476

African (AFR) AF: 0.000120 AC: 5 AN: 41590

American (AMR) AF: 0.0000654 AC: 1 AN: 15290

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 3468

East Asian (EAS) AF: 0.00 AC: 0 AN: 5178

South Asian (SAS) AF: 0.00 AC: 0 AN: 4828

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10628

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

European-Non Finnish (NFE) AF: 0.000470 AC: 32 AN: 68020

Other (OTH) AF: 0.00 AC: 0 AN: 2112

Alfa AF: 0.000392 Hom.: 0

Bravo AF: 0.000253

TwinsUK AF: 0.000270 AC: 1

ALSPAC AF: 0.00 AC: 0

ESP6500AA AF: 0.00 AC: 0

ESP6500EA AF: 0.000602 AC: 5

ExAC AF: 0.000215 AC: 26

ClinVar

ClinVar submissions as Germline

Significance: Conflicting classifications of pathogenicity

Revision: criteria provided, conflicting classifications

Pathogenic	VUS	Benign	Condition
-	3	4	not provided (7)
-	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	-	Dilated cardiomyopathy 1G (1)
-	1	-	Early-onset myopathy with fatal cardiomyopathy (1)
-	-	1	Myopathy, myofibrillar, 9, with early respiratory failure (1)
-	-	1	not specified (1)
-	-	1	Tibial muscular dystrophy (1)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.83
BayesDel_addAF	Benign	-0.25	T
BayesDel_noAF	Benign	-0.27
CADD	Benign	22
DANN	Benign	0.97
Eigen	Pathogenic	1.0
Eigen_PC	Pathogenic	0.94
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.87	D
M_CAP	Benign	0.035	D
MetaRNN	Benign	0.16	T
MetaSVM	Uncertain	0.43	D
PhyloP100		7.7
PrimateAI	Uncertain	0.59	T
PROVEAN	Uncertain	-2.9	D
REVEL	Uncertain	0.63
Sift	Benign	0.15	T
Polyphen		1.0	D
Vest4		0.24
MVP		0.40
MPC		0.42
ClinPred		0.094	T
GERP RS		5.9
Mutation Taster		=54/46	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: rs200866883; hg19: chr2-179590139;