2-178590562-G-C

Variant names:

• chr2-178590562-G-C
• rs397517648
• NM_001267550.2:c.61163C>G

Variant summary

Our verdict is Uncertain significance. The variant received 1 ACMG points: 2P and 1B. PM2 BP4

The NM_001267550.2(TTN):​c.61163C>G​(p.Ala20388Gly) variant causes a missense change. The variant allele was found at a frequency of 0.00000248 in 1,612,450 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 Uncertain significance (★).

• Frequency:
  • Genomes: 𝑓 0.0000066 (0 hom., cov: 32)
  • Exomes 𝑓: 0.0000021 (0 hom.)
• Consequence: TTN NM_001267550.2 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 5.85
• Publications: 1 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.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.3419196).

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.61163C>G	p.Ala20388Gly	missense	Exon 304 of 363	NP_001254479.2	Q8WZ42-12
	TTN	NM_001256850.1		c.56240C>G	p.Ala18747Gly	missense	Exon 254 of 313	NP_001243779.1	Q8WZ42-1
	TTN	NM_133378.4		c.53459C>G	p.Ala17820Gly	missense	Exon 253 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.61163C>G	p.Ala20388Gly	missense	Exon 304 of 363	ENSP00000467141.1	Q8WZ42-12
	TTN	ENST00000446966.2	TSL:1	c.61007C>G	p.Ala20336Gly	missense	Exon 302 of 361	ENSP00000408004.2	A0A1B0GXE3
	TTN	ENST00000436599.2	TSL:1	c.60887C>G	p.Ala20296Gly	missense	Exon 302 of 361	ENSP00000405517.2	A0A0C4DG59

Frequencies

GnomAD3 genomes AF: 0.00000658 AC: 1 AN: 152010 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.0000241

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: 0.00

Gnomad OTH AF: 0.00

GnomAD2 exomes AF: 0.00000405 AC: 1 AN: 247144 AF XY: 0.00000746

Gnomad AFR exome AF: 0.0000651

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000205 AC: 3 AN: 1460440 Hom.: 0 Cov.: 35 AF XY: 0.00000413 AC XY: 3 AN XY: 726442

African (AFR) AF: 0.0000898 AC: 3 AN: 33414

American (AMR) AF: 0.00 AC: 0 AN: 44624

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26074

East Asian (EAS) AF: 0.00 AC: 0 AN: 39610

South Asian (SAS) AF: 0.00 AC: 0 AN: 86044

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53326

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5752

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 1111276

Other (OTH) AF: 0.00 AC: 0 AN: 60320

GnomAD4 genome AF: 0.00000658 AC: 1 AN: 152010 Hom.: 0 Cov.: 32 AF XY: 0.00 AC XY: 0 AN XY: 74234

African (AFR) AF: 0.0000241 AC: 1 AN: 41424

American (AMR) AF: 0.00 AC: 0 AN: 15250

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 3470

East Asian (EAS) AF: 0.00 AC: 0 AN: 5150

South Asian (SAS) AF: 0.00 AC: 0 AN: 4824

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10610

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

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 67968

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

Alfa AF: 0.00 Hom.: 0

Bravo AF: 0.0000113

ClinVar

ClinVar submissions

Significance: Uncertain significance

Revision: criteria provided, single submitter

Pathogenic	VUS	Benign	Condition
-	1	-	not specified (1)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Uncertain	0.54
BayesDel_addAF	Benign	-0.19	T
BayesDel_noAF	Benign	-0.33
CADD	Benign	21
DANN	Benign	0.87
Eigen	Pathogenic	0.91
Eigen_PC	Pathogenic	0.89
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Uncertain	0.92	D
M_CAP	Benign	0.017	T
MetaRNN	Benign	0.34	T
MetaSVM	Benign	-0.37	T
MutationAssessor	Uncertain	2.8	M
PhyloP100		5.9
PrimateAI	Uncertain	0.57	T
PROVEAN	Uncertain	-3.2	D
REVEL	Uncertain	0.37
Sift	Benign	0.069	T
Polyphen		1.0	D
Vest4		0.36
MutPred		0.54		Loss of stability (P = 0.0498)
MVP		0.25
MPC		0.44
ClinPred		0.22	T
GERP RS		6.1
Mutation Taster		=35/65	disease causing

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.060		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: rs397517648; hg19: chr2-179455289;