2-178556971-A-G

Position:

chr2-178556971-A-G

Variant summary

Our verdict is Likely benign. Variant got -3 ACMG points: 1P and 4B. PP2BP4_Strong

The NM_001267550.2(TTN):c.88183T>C(p.Phe29395Leu) variant causes a missense change. The variant allele was found at a frequency of 0.0000366 in 1,613,824 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 12/19 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).

Frequency

Genomes: 𝑓 0.000098 ( 0 hom., cov: 33)

Exomes 𝑓: 0.000030 ( 0 hom. )

Consequence

TTN
NM_001267550.2 missense

Scores

Clinical Significance

Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:4B:1

Conservation

PhyloP100: 6.12

Variant links:

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 links:

(HGNC:):

links:

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]

TTN-AS1 links:

Genome browser will be placed here

ACMG classification

Classification made for transcript

Verdict is Likely_benign. Variant got -3 ACMG points.

PP2

Missense variant in gene, where missense usually causes diseases (based on misZ statistic), TTN. . Gene score misZ -1.1021 (greater than the threshold 3.09). Trascript score misZ 6.9794 (greater than threshold 3.09). GenCC has associacion of gene with dilated cardiomyopathy, tibial muscular dystrophy, early-onset myopathy with fatal cardiomyopathy, autosomal recessive centronuclear myopathy, hypertrophic cardiomyopathy, hypertrophic cardiomyopathy 9, TTN-related myopathy, dilated cardiomyopathy 1G, arrhythmogenic right ventricular cardiomyopathy, myopathy, myofibrillar, 9, with early respiratory failure, familial isolated dilated cardiomyopathy, childhood-onset progressive contractures-limb-girdle weakness-muscle dystrophy syndrome, autosomal recessive limb-girdle muscular dystrophy type 2J.

BP4

Computational evidence support a benign effect (MetaRNN=0.007660389).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
TTN	NM_001267550.2 linkuse as main transcript	c.88183T>C	p.Phe29395Leu	missense_variant	330/363	ENST00000589042.5	NP_001254479.2
TTN-AS1	NR_038272.1 linkuse as main transcript	n.2043+14610A>G		intron_variant, non_coding_transcript_variant

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris
TTN	ENST00000589042.5 linkuse as main transcript	c.88183T>C	p.Phe29395Leu	missense_variant	330/363	5	NM_001267550.2	ENSP00000467141	P1
	ENST00000624360.1 linkuse as main transcript	n.2411A>G		non_coding_transcript_exon_variant	1/1
TTN-AS1	ENST00000659121.1 linkuse as main transcript	n.416+33335A>G		intron_variant, non_coding_transcript_variant

Frequencies

GnomAD3 genomes

AF:

0.0000986

AC:

AN:

152184

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.00

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.00

Gnomad ASJ

AF:

0.00

Gnomad EAS

AF:

0.00270

Gnomad SAS

AF:

0.000207

Gnomad FIN

AF:

0.00

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.00

Gnomad OTH

AF:

0.00

GnomAD3 exomes

AF:

0.000133

AC:

AN:

248652

Hom.:

AF XY:

0.000133

AC XY:

AN XY:

134884

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.00

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.00174

Gnomad SAS exome

AF:

0.0000654

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.00

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.0000301

AC:

AN:

1461522

Hom.:

Cov.:

AF XY:

0.0000303

AC XY:

AN XY:

727038

show subpopulations

Gnomad4 AFR exome

AF:

0.00

Gnomad4 AMR exome

AF:

0.00

Gnomad4 ASJ exome

AF:

0.00

Gnomad4 EAS exome

AF:

0.000833

Gnomad4 SAS exome

AF:

0.0000348

Gnomad4 FIN exome

AF:

0.00

Gnomad4 NFE exome

AF:

0.00

Gnomad4 OTH exome

AF:

0.000133

GnomAD4 genome

AF:

0.0000985

AC:

AN:

152302

Hom.:

Cov.:

AF XY:

0.000134

AC XY:

AN XY:

74476

show subpopulations

Gnomad4 AFR

AF:

0.00

Gnomad4 AMR

AF:

0.00

Gnomad4 ASJ

AF:

0.00

Gnomad4 EAS

AF:

0.00270

Gnomad4 SAS

AF:

0.000207

Gnomad4 FIN

AF:

0.00

Gnomad4 NFE

AF:

0.00

Gnomad4 OTH

AF:

0.00

Alfa

AF:

0.0000329

Hom.:

Bravo

AF:

0.0000718

ExAC

AF:

0.000132

AC:

Asia WGS

AF:

0.000866

AC:

AN:

3478

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:4Benign:1

Revision: criteria provided, conflicting classifications

LINK: link

Submissions by phenotype

not specified

Uncertain:2

Uncertain significance, criteria provided, single submitter	clinical testing	GeneDx	Jul 08, 2014	Missense variants in the TTN gene are considered 'unclassified' if they are not previously reported in the literature and do not have >1% frequency in the population to be considered a polymorphism. Research indicates that truncating mutations in the TTN gene are expected to account for approximately 25% of familial and 18% of sporadic idiopathic DCM; however, truncating variants in the TTN gene have been reported in approximately 3% of reported control alleles. There has been little investigation into non-truncating variants. (Herman D et al. Truncations of titin causing dilated cardiomyopathy. N Eng J Med 366:619-628, 2012) The variant is found in CARDIOMYOPATHY panel(s). -
Uncertain significance, criteria provided, single submitter	clinical testing	Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine	Oct 17, 2012	Variant classified as Uncertain Significance - Favor Benign. The Phe26827Leu var iant in TTN has not been reported in the literature nor previously identified by our laboratory. It has been identified in 1/194 Han Chinese chromosomes from a broad population by the 1000 Genomes project (dbSNP rs55940667). Computational analyses (biochemical amino acid properties, conservation, AlignGVGD, PolyPhen2, and SIFT) do not provide strong support for or against an impact to the protein , though dolphin carries a leucine (Leu; this variant) despite high amino acid c onservation nearby, suggesting that this variant may be tolerated. This variant is more likely benign but at this time, additional information is needed to full y assess its clinical significance. -

not provided

Uncertain:1

Uncertain significance, criteria provided, single submitter

research

Biesecker Lab/Clinical Genomics Section, National Institutes of Health

Jun 24, 2013

- -

Cardiovascular phenotype

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Sep 23, 2013

The p.F26827L variant (also known as c.80479T>C) is located in coding exon 278 of the TTNgene. This alteration results from a T to C substitution at nucleotide position 80479. The phenylalanine at codon 26827 is replaced by leucine, an amino acid with highly similar properties.This variant was previously reported in the SNPDatabase as rs55940667. Based on data from the 1000 Genomes Project, the C-allele has an overall frequency of approximately 0.05% (1/2184). The highest observed frequency was 0.52% (1/194) Han Chinese chromosomes studied. This amino acid position is not conserved on sequence alignment. This variant is predicted to be benign by PolyPhen in silico analyses. Since supporting evidence is limited at this time, the clinical significance of p.F26827L remains unclear. -

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

Benign:1

Likely benign, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Nov 30, 2023

- -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Pathogenic

0.87

BayesDel_addAF

Benign

-0.36

BayesDel_noAF

Benign

-0.29

CADD

Benign

DANN

Benign

0.96

Eigen

Benign

-0.034

Eigen_PC

Benign

0.10

FATHMM_MKL

Uncertain

0.97

LIST_S2

Benign

0.74

T;T;T;.;T;T;T

M_CAP

Benign

0.025

MetaRNN

Benign

0.0077

T;T;T;T;T;T;T

MetaSVM

Benign

-0.92

MutationAssessor

Benign

1.7

.;.;.;L;.;.;L

MutationTaster

Benign

1.0

D;D;D;D;D;D

PrimateAI

Uncertain

0.67

PROVEAN

Uncertain

-3.8

D;D;.;.;D;D;.

REVEL

Benign

0.22

Sift

Uncertain

0.010

D;D;.;.;D;D;.

Polyphen

0.0080

.;.;.;B;.;.;B

Vest4

0.43

MutPred

0.64

.;.;.;Loss of catalytic residue at F27754 (P = 0.1234);.;.;Loss of catalytic residue at F27754 (P = 0.1234);

MVP

0.30

MPC

0.10

ClinPred

0.16

GERP RS

4.7

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

Below is the list of publications found by LitVar. It may be empty.

Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

LitVar

Other links and lift over