chr2-178583772-A-G

Variant names:

• chr2-178583772-A-G
• rs745626132
• NM_001267550.2:c.65410T>C

Variant summary

Our verdict is Uncertain significance. The variant received 1 ACMG points: 1P and 0B. PP3

The NM_001267550.2(TTN):​c.65410T>C​(p.Trp21804Arg) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.0000137 in 1,611,246 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).

• Frequency:
  • Genomes: 𝑓 0.0000066 (0 hom., cov: 32)
  • Exomes 𝑓: 0.000014 (0 hom.)
• Consequence: TTN NM_001267550.2 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:7 B:2
• Conservation: PhyloP100: 9.27
• 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: Uncertain_significance. The variant received 1 ACMG points.

• PP3: MetaRNN computational evidence supports a deleterious effect, 0.773

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.65410T>C	p.Trp21804Arg	missense	Exon 312 of 363	NP_001254479.2	Q8WZ42-12
	TTN	NM_001256850.1		c.60487T>C	p.Trp20163Arg	missense	Exon 262 of 313	NP_001243779.1	Q8WZ42-1
	TTN	NM_133378.4		c.57706T>C	p.Trp19236Arg	missense	Exon 261 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.65410T>C	p.Trp21804Arg	missense	Exon 312 of 363	ENSP00000467141.1	Q8WZ42-12
	TTN	ENST00000446966.2	TSL:1	c.65254T>C	p.Trp21752Arg	missense	Exon 310 of 361	ENSP00000408004.2	A0A1B0GXE3
	TTN	ENST00000436599.2	TSL:1	c.65134T>C	p.Trp21712Arg	missense	Exon 310 of 361	ENSP00000405517.2	A0A0C4DG59

Frequencies

GnomAD3 genomes AF: 0.00000658 AC: 1 AN: 152074 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.000194

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: 0.0000286 AC: 7 AN: 244666 AF XY: 0.0000377

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.000400

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.0000144 AC: 21 AN: 1459172 Hom.: 0 Cov.: 31 AF XY: 0.0000179 AC XY: 13 AN XY: 725654

African (AFR) AF: 0.00 AC: 0 AN: 33422

American (AMR) AF: 0.00 AC: 0 AN: 44510

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26050

East Asian (EAS) AF: 0.000533 AC: 21 AN: 39390

South Asian (SAS) AF: 0.00 AC: 0 AN: 85822

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53254

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5758

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 1110718

Other (OTH) AF: 0.00 AC: 0 AN: 60248

GnomAD4 genome AF: 0.00000658 AC: 1 AN: 152074 Hom.: 0 Cov.: 32 AF XY: 0.0000135 AC XY: 1 AN XY: 74264

African (AFR) AF: 0.00 AC: 0 AN: 41434

American (AMR) AF: 0.00 AC: 0 AN: 15262

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

East Asian (EAS) AF: 0.000194 AC: 1 AN: 5154

South Asian (SAS) AF: 0.00 AC: 0 AN: 4834

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10618

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 316

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 67984

Other (OTH) AF: 0.00 AC: 0 AN: 2088

Alfa AF: 0.00 Hom.: 0

ExAC AF: 0.0000249 AC: 3

Asia WGS AF: 0.000289 AC: 1 AN: 3478

ClinVar

ClinVar submissions

Significance: Conflicting classifications of pathogenicity

Revision: criteria provided, conflicting classifications

Pathogenic	VUS	Benign	Condition
-	2	-	Dilated cardiomyopathy 1G (2)
-	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;C1861065:Hypertrophic cardiomyopathy 9 (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
AlphaMissense	Pathogenic	1.0
BayesDel_addAF	Benign	-0.041	T
BayesDel_noAF	Uncertain	0.040
CADD	Uncertain	23
DANN	Benign	0.93
Eigen	Pathogenic	1.0
Eigen_PC	Pathogenic	0.97
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Benign	0.82	T
M_CAP	Benign	0.039	D
MetaRNN	Pathogenic	0.77	D
MetaSVM	Uncertain	0.35	D
MutationAssessor	Pathogenic	4.1	H
PhyloP100		9.3
PrimateAI	Pathogenic	0.86	D
PROVEAN	Pathogenic	-11	D
REVEL	Pathogenic	0.67
Sift	Pathogenic	0.0	D
Polyphen		1.0	D
Vest4		0.65
MutPred		0.84		Gain of disorder (P = 0.0399)
MVP		0.79
MPC		0.62
ClinPred		0.49	T
GERP RS		6.0
Mutation Taster		=4/96	disease causing

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.020		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: rs745626132; hg19: chr2-179448499;