2-178593830-A-T

Variant names:

• chr2-178593830-A-T
• rs374118468
• NM_001267550.2:c.58470T>A

Variant summary

Our verdict is Likely benign. The variant received -2 ACMG points: 0P and 2B. BP4_Moderate

The NM_001267550.2(TTN):​c.58470T>A​(p.Asp19490Glu) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000236 in 1,612,938 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 15/20 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars). Another nucleotide change resulting in the same amino acid substitution has been previously reported as Uncertain significance in ClinVar. Synonymous variant affecting the same amino acid position (i.e. D19490D) has been classified as Likely benign.

• Frequency:
  • Genomes: 𝑓 0.000053 (0 hom., cov: 32)
  • Exomes 𝑓: 0.000021 (0 hom.)
• Consequence: TTN NM_001267550.2 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:6 B:1
• Conservation: PhyloP100: 0.495
• 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 -2 ACMG points.

• BP4: Computational evidence support a benign effect (MetaRNN=0.08849704).

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.58470T>A	p.Asp19490Glu	missense	Exon 298 of 363	NP_001254479.2	Q8WZ42-12
	TTN	NM_001256850.1		c.53547T>A	p.Asp17849Glu	missense	Exon 248 of 313	NP_001243779.1	Q8WZ42-1
	TTN	NM_133378.4		c.50766T>A	p.Asp16922Glu	missense	Exon 247 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.58470T>A	p.Asp19490Glu	missense	Exon 298 of 363	ENSP00000467141.1	Q8WZ42-12
	TTN	ENST00000446966.2	TSL:1	c.58314T>A	p.Asp19438Glu	missense	Exon 296 of 361	ENSP00000408004.2	A0A1B0GXE3
	TTN	ENST00000436599.2	TSL:1	c.58194T>A	p.Asp19398Glu	missense	Exon 296 of 361	ENSP00000405517.2	A0A0C4DG59

Frequencies

GnomAD3 genomes AF: 0.0000526 AC: 8 AN: 152082 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.0000483

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.0000655

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.000388

Gnomad SAS AF: 0.000414

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.00

Gnomad OTH AF: 0.000478

GnomAD2 exomes AF: 0.0000405 AC: 10 AN: 246882 AF XY: 0.0000373

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.000171

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.000167

GnomAD4 exome AF: 0.0000205 AC: 30 AN: 1460856 Hom.: 0 Cov.: 35 AF XY: 0.0000206 AC XY: 15 AN XY: 726680

African (AFR) AF: 0.00 AC: 0 AN: 33454

American (AMR) AF: 0.0000224 AC: 1 AN: 44636

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26118

East Asian (EAS) AF: 0.000101 AC: 4 AN: 39446

South Asian (SAS) AF: 0.000209 AC: 18 AN: 86222

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53314

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5760

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 1111578

Other (OTH) AF: 0.000116 AC: 7 AN: 60328

GnomAD4 genome AF: 0.0000526 AC: 8 AN: 152082 Hom.: 0 Cov.: 32 AF XY: 0.0000808 AC XY: 6 AN XY: 74276

African (AFR) AF: 0.0000483 AC: 2 AN: 41436

American (AMR) AF: 0.0000655 AC: 1 AN: 15260

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

East Asian (EAS) AF: 0.000388 AC: 2 AN: 5158

South Asian (SAS) AF: 0.000414 AC: 2 AN: 4834

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10624

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

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 67982

Other (OTH) AF: 0.000478 AC: 1 AN: 2090

Alfa AF: 0.0000565 Hom.: 0

Bravo AF: 0.0000718

ExAC AF: 0.0000331 AC: 4

Asia WGS AF: 0.00289 AC: 10 AN: 3478

ClinVar

ClinVar submissions

Significance: Conflicting classifications of pathogenicity

Revision: criteria provided, conflicting classifications

Pathogenic	VUS	Benign	Condition
-	3	1	not provided (4)
-	1	-	Autosomal recessive limb-girdle muscular dystrophy type 2J;C1858763:Dilated cardiomyopathy 1G (1)
-	1	-	Cardiomyopathy (1)
-	1	-	Cardiovascular phenotype (1)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.13
BayesDel_addAF	Benign	-0.35	T
BayesDel_noAF	Benign	-0.45
CADD	Benign	13
DANN	Benign	0.89
Eigen	Benign	0.19
Eigen_PC	Benign	0.18
FATHMM_MKL	Uncertain	0.92	D
LIST_S2	Benign	0.82	T
M_CAP	Benign	0.022	T
MetaRNN	Benign	0.088	T
MetaSVM	Benign	-0.82	T
MutationAssessor	Benign	0.51	N
PhyloP100		0.49
PrimateAI	Uncertain	0.49	T
PROVEAN	Benign	-2.3	N
REVEL	Benign	0.14
Sift	Benign	0.17	T
Polyphen		1.0	D
Vest4		0.34
MutPred		0.35		Gain of loop (P = 0.1069)
MVP		0.26
MPC		0.39
ClinPred		0.14	T
GERP RS		1.8
Mutation Taster		=65/35	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: rs374118468; hg19: chr2-179458557;