rs773286477

chr2-178570386-C-T

Variant summary

Our verdict is Uncertain significance. Variant got 0 ACMG points: 1P and 1B. PP2 BP4

The NM_001267550.2(TTN):c.75746G>A(p.Arg25249His) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.0000341 in 1,613,070 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. R25249C) has been classified as Likely benign.

• Frequency:
  • Genomes: 𝑓 0.000020 (0 hom., cov: 33)
  • Exomes 𝑓: 0.000036 (0 hom.)
• Consequence: TTN NM_001267550.2 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:3
• Conservation: PhyloP100: 7.86

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

Verdict is Uncertain_significance. Variant got 0 ACMG points.

• PP2: Missense variant where missense usually causes diseases, TTN
• BP4: Computational evidence support a benign effect (MetaRNN=0.2761829).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
TTN	NM_001267550.2	c.75746G>A	p.Arg25249His	missense_variant	326/363	ENST00000589042.5
TTN-AS1	NR_038272.1	n.2044-12186C>T		intron_variant, non_coding_transcript_variant

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
TTN	ENST00000589042.5	c.75746G>A	p.Arg25249His	missense_variant	326/363	5	NM_001267550.2	P1
TTN-AS1	ENST00000659121.1	n.417-27210C>T		intron_variant, non_coding_transcript_variant

Frequencies

GnomAD3 genomes AF: 0.0000197 AC: 3 AN: 152034 Hom.: 0 Cov.: 33

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.0000656

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

GnomAD3 exomes AF: 0.0000445 AC: 11 AN: 247036 Hom.: 0 AF XY: 0.0000746 AC XY: 10 AN XY: 134128

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad SAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.0000898

Gnomad OTH exome AF: 0.000167

GnomAD4 exome AF: 0.0000356 AC: 52 AN: 1461036 Hom.: 0 Cov.: 40 AF XY: 0.0000399 AC XY: 29 AN XY: 726812

Gnomad4 AFR exome AF: 0.0000299

Gnomad4 AMR exome AF: 0.0000447

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.0000759

Gnomad4 SAS exome AF: 0.0000348

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.0000342

Gnomad4 OTH exome AF: 0.0000829

GnomAD4 genome AF: 0.0000197 AC: 3 AN: 152034 Hom.: 0 Cov.: 33 AF XY: 0.0000269 AC XY: 2 AN XY: 74240

Gnomad4 AFR AF: 0.00

Gnomad4 AMR AF: 0.0000656

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.0000294

Gnomad4 OTH AF: 0.00

Alfa AF: 0.0000823 Hom.: 0

Bravo AF: 0.0000302

ExAC AF: 0.0000414 AC: 5

EpiCase AF: 0.00

EpiControl AF: 0.000119

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:3

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not provided Uncertain:2

Uncertain significance, criteria provided, single submitter	clinical testing	Eurofins Ntd Llc (ga)	Jul 18, 2015	- -
Uncertain significance, criteria provided, single submitter	clinical testing	Revvity Omics, Revvity	May 06, 2022	- -

Autosomal recessive limb-girdle muscular dystrophy type 2J;C1858763:Dilated cardiomyopathy 1G Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

Dec 21, 2017

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Uncertain	0.41
BayesDel_addAF	Benign	-0.17	T
BayesDel_noAF	Benign	-0.29
Cadd	Benign	22
Dann	Benign	0.91
Eigen	Pathogenic	0.85
Eigen_PC	Pathogenic	0.84
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Pathogenic	0.97	D;D;D;.;D;D;D
M_CAP	Benign	0.015	T
MetaRNN	Benign	0.28	T;T;T;T;T;T;T
MetaSVM	Benign	-0.40	T
MutationTaster	Benign	1.0	D;D;D;D;D;D
PrimateAI	Uncertain	0.74	T
PROVEAN	Uncertain	-3.5	D;D;.;.;D;D;.
REVEL	Uncertain	0.35
Sift	Uncertain	0.0050	D;D;.;.;D;D;.
Polyphen		1.0	.;.;.;D;.;.;D
Vest4		0.35
MutPred		0.58		.;.;.;Loss of catalytic residue at R23608 (P = 0.0303);.;.;Loss of catalytic residue at R23608 (P = 0.0303);
MVP		0.33
MPC		0.52
ClinPred		0.30	T
GERP RS		5.6

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

Publications

LitVar

Other links and lift over

dbSNP: rs773286477; hg19: chr2-179435113;