2-178597574-C-G

Variant names:

• chr2-178597574-C-G
• rs750947988
• NM_001267550.2:c.57508G>C

Variant summary

Our verdict is Uncertain significance. The variant received 3 ACMG points: 3P and 0B. PM2 PP3

The NM_001267550.2(TTN):​c.57508G>C​(p.Gly19170Arg) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.0000031 in 1,612,418 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar. Another nucleotide change resulting in the same amino acid substitution has been previously reported as Uncertain significance in ClinVar.

• Frequency:
  • Genomes: 𝑓 0.0000066 (0 hom., cov: 32)
  • Exomes 𝑓: 0.0000027 (0 hom.)
• Consequence: TTN NM_001267550.2 missense
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 7.85
• Publications: 3 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 3 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.827

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.57508G>C	p.Gly19170Arg	missense	Exon 294 of 363	NP_001254479.2	Q8WZ42-12
	TTN	NM_001256850.1		c.52585G>C	p.Gly17529Arg	missense	Exon 244 of 313	NP_001243779.1	Q8WZ42-1
	TTN	NM_133378.4		c.49804G>C	p.Gly16602Arg	missense	Exon 243 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.57508G>C	p.Gly19170Arg	missense	Exon 294 of 363	ENSP00000467141.1	Q8WZ42-12
	TTN	ENST00000446966.2	TSL:1	c.57352G>C	p.Gly19118Arg	missense	Exon 292 of 361	ENSP00000408004.2	A0A1B0GXE3
	TTN	ENST00000436599.2	TSL:1	c.57232G>C	p.Gly19078Arg	missense	Exon 292 of 361	ENSP00000405517.2	A0A0C4DG59

Frequencies

GnomAD3 genomes AF: 0.00000658 AC: 1 AN: 151990 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: 0.00

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.0000147

Gnomad OTH AF: 0.00

GnomAD4 exome AF: 0.00000274 AC: 4 AN: 1460428 Hom.: 0 Cov.: 31 AF XY: 0.00000413 AC XY: 3 AN XY: 726430

African (AFR) AF: 0.00 AC: 0 AN: 33420

American (AMR) AF: 0.00 AC: 0 AN: 44576

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26104

East Asian (EAS) AF: 0.00 AC: 0 AN: 39450

South Asian (SAS) AF: 0.00 AC: 0 AN: 86082

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53328

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5754

European-Non Finnish (NFE) AF: 0.00000270 AC: 3 AN: 1111414

Other (OTH) AF: 0.0000166 AC: 1 AN: 60300

GnomAD4 genome AF: 0.00000658 AC: 1 AN: 151990 Hom.: 0 Cov.: 32 AF XY: 0.00 AC XY: 0 AN XY: 74214

African (AFR) AF: 0.00 AC: 0 AN: 41406

American (AMR) AF: 0.00 AC: 0 AN: 15240

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 3464

East Asian (EAS) AF: 0.00 AC: 0 AN: 5146

South Asian (SAS) AF: 0.00 AC: 0 AN: 4822

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10606

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

European-Non Finnish (NFE) AF: 0.0000147 AC: 1 AN: 67988

Other (OTH) AF: 0.00 AC: 0 AN: 2090

Alfa AF: 0.00 Hom.: 0

Bravo AF: 0.00000756

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.81
BayesDel_addAF	Pathogenic	0.20	D
BayesDel_noAF	Uncertain	0.060
CADD	Benign	23
DANN	Benign	0.97
Eigen	Pathogenic	1.1
Eigen_PC	Pathogenic	1.0
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.94	D
M_CAP	Benign	0.033	D
MetaRNN	Pathogenic	0.83	D
MetaSVM	Uncertain	0.68	D
MutationAssessor	Pathogenic	3.4	M
PhyloP100		7.8
PrimateAI	Uncertain	0.61	T
PROVEAN	Pathogenic	-6.2	D
REVEL	Uncertain	0.64
Sift	Pathogenic	0.0	D
Polyphen		1.0	D
Vest4		0.56
MutPred		0.85		Gain of MoRF binding (P = 0.0182)
MVP		0.62
MPC		0.51
ClinPred		0.98	D
GERP RS		6.1
Mutation Taster		=66/34	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: rs750947988; hg19: chr2-179462301;