2-178546794-C-T

Variant names:

• chr2-178546794-C-T
• rs920039018
• NM_001267550.2:c.94634G>A

Variant summary

Our verdict is Likely benign. The variant received -1 ACMG points: 0P and 1B. BP4

The NM_001267550.2(TTN):​c.94634G>A​(p.Arg31545His) variant causes a missense change. The variant allele was found at a frequency of 0.0000161 in 1,613,562 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 (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R31545C) has been classified as Likely benign.

• Frequency:
  • Genomes: 𝑓 0.000013 (0 hom., cov: 32)
  • Exomes 𝑓: 0.000016 (0 hom.)
• Consequence: TTN NM_001267550.2 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: 6.16
• Publications: 0 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: Likely_benign. The variant received -1 ACMG points.

• BP4: Computational evidence support a benign effect (MetaRNN=0.33369377).

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.94634G>A	p.Arg31545His	missense	Exon 341 of 363	NP_001254479.2	Q8WZ42-12
	TTN	NM_001256850.1		c.89711G>A	p.Arg29904His	missense	Exon 291 of 313	NP_001243779.1	Q8WZ42-1
	TTN	NM_133378.4		c.86930G>A	p.Arg28977His	missense	Exon 290 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.94634G>A	p.Arg31545His	missense	Exon 341 of 363	ENSP00000467141.1	Q8WZ42-12
	TTN	ENST00000446966.2	TSL:1	c.94478G>A	p.Arg31493His	missense	Exon 339 of 361	ENSP00000408004.2	A0A1B0GXE3
	TTN	ENST00000436599.2	TSL:1	c.94358G>A	p.Arg31453His	missense	Exon 339 of 361	ENSP00000405517.2	A0A0C4DG59

Frequencies

GnomAD3 genomes AF: 0.0000131 AC: 2 AN: 152126 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: 0.0000294

Gnomad OTH AF: 0.00

GnomAD2 exomes AF: 0.0000121 AC: 3 AN: 247970 AF XY: 0.00000744

Gnomad AFR exome AF: 0.0000646

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad FIN exome AF: 0.0000465

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.0000164 AC: 24 AN: 1461436 Hom.: 0 Cov.: 33 AF XY: 0.0000165 AC XY: 12 AN XY: 727000

African (AFR) AF: 0.0000299 AC: 1 AN: 33462

American (AMR) AF: 0.00 AC: 0 AN: 44716

Ashkenazi Jewish (ASJ) AF: 0.0000383 AC: 1 AN: 26124

East Asian (EAS) AF: 0.0000252 AC: 1 AN: 39680

South Asian (SAS) AF: 0.0000232 AC: 2 AN: 86246

European-Finnish (FIN) AF: 0.0000187 AC: 1 AN: 53384

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

European-Non Finnish (NFE) AF: 0.0000162 AC: 18 AN: 1111700

Other (OTH) AF: 0.00 AC: 0 AN: 60360

GnomAD4 genome AF: 0.0000131 AC: 2 AN: 152126 Hom.: 0 Cov.: 32 AF XY: 0.00 AC XY: 0 AN XY: 74306

African (AFR) AF: 0.00 AC: 0 AN: 41430

American (AMR) AF: 0.00 AC: 0 AN: 15268

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

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

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

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: 0.0000294 AC: 2 AN: 68022

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

Alfa AF: 0.00 Hom.: 0

Bravo AF: 0.0000113

ClinVar

ClinVar submissions as Germline

Significance: Uncertain significance

Revision: criteria provided, multiple submitters, no conflicts

Pathogenic	VUS	Benign	Condition
-	1	-	Autosomal recessive limb-girdle muscular dystrophy type 2J;C1858763:Dilated cardiomyopathy 1G (1)
-	1	-	Cardiovascular phenotype (1)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Uncertain	0.40
BayesDel_addAF	Benign	-0.15	T
BayesDel_noAF	Benign	-0.27
CADD	Uncertain	23
DANN	Uncertain	0.98
Eigen	Pathogenic	0.88
Eigen_PC	Pathogenic	0.87
FATHMM_MKL	Pathogenic	0.97	D
LIST_S2	Uncertain	0.93	D
M_CAP	Benign	0.014	T
MetaRNN	Benign	0.33	T
MetaSVM	Uncertain	-0.26	T
MutationAssessor	Uncertain	2.2	M
PhyloP100		6.2
PrimateAI	Uncertain	0.60	T
PROVEAN	Uncertain	-3.5	D
REVEL	Uncertain	0.39
Sift	Uncertain	0.0080	D
Polyphen		1.0	D
Vest4		0.41
MutPred		0.55		Loss of ubiquitination at K29905 (P = 0.057)
MVP		0.34
MPC		0.50
ClinPred		0.65	D
GERP RS		6.0
Mutation Taster		=90/10	polymorphism

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: rs920039018; hg19: chr2-179411521; COSMIC: COSV59902824; COSMIC: COSV59902824;