2-178549450-G-A

Position:

chr2-178549450-G-A

Variant summary

Our verdict is Benign. Variant got -12 ACMG points: 1P and 13B. PP2BP4_StrongBP6BS1BS2

The NM_001267550.2(TTN):c.92176C>T(p.Pro30726Ser) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00267 in 1,607,122 control chromosomes in the GnomAD database, including 16 homozygotes. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).

Frequency

Genomes: 𝑓 0.0020 ( 3 hom., cov: 33)

Exomes 𝑓: 0.0027 ( 13 hom. )

Consequence

TTN
NM_001267550.2 missense

Scores

Clinical Significance

Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:1U:8B:18

Conservation

PhyloP100: 8.15

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 Benign. Variant got -12 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=0.008055747).

BP6

Variant 2-178549450-G-A is Benign according to our data. Variant chr2-178549450-G-A is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 47520.We mark this variant Likely_benign, oryginal submissions are: {Likely_benign=7, Likely_pathogenic=1, Benign=5, Uncertain_significance=8}. Variant chr2-178549450-G-A is described in Lovd as [Benign]. Variant chr2-178549450-G-A is described in Lovd as [Likely_benign].

BS1

Variant frequency is greater than expected in population sas. gnomad4 allele frequency = 0.00198 (302/152258) while in subpopulation SAS AF= 0.0058 (28/4824). AF 95% confidence interval is 0.00413. There are 3 homozygotes in gnomad4. There are 161 alleles in male gnomad4 subpopulation. Median coverage is 33. This position pass quality control queck.

BS2

High Homozygotes in GnomAd4 at 3 AD,AR gene

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
TTN	NM_001267550.2 linkuse as main transcript	c.92176C>T	p.Pro30726Ser	missense_variant	339/363	ENST00000589042.5	NP_001254479.2
TTN-AS1	NR_038272.1 linkuse as main transcript	n.2043+7089G>A		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.92176C>T	p.Pro30726Ser	missense_variant	339/363	5	NM_001267550.2	ENSP00000467141	P1
	ENST00000603415.1 linkuse as main transcript	n.567G>A		non_coding_transcript_exon_variant	1/1
TTN-AS1	ENST00000659121.1 linkuse as main transcript	n.416+25814G>A		intron_variant, non_coding_transcript_variant

Frequencies

GnomAD3 genomes

AF:

0.00199

AC:

302

AN:

152140

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.000386

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.000720

Gnomad ASJ

AF:

0.00259

Gnomad EAS

AF:

0.00

Gnomad SAS

AF:

0.00580

Gnomad FIN

AF:

0.00179

Gnomad MID

AF:

0.0127

Gnomad NFE

AF:

0.00310

Gnomad OTH

AF:

0.00191

GnomAD3 exomes

AF:

0.00268

AC:

659

AN:

245714

Hom.:

AF XY:

0.00307

AC XY:

410

AN XY:

133366

show subpopulations

Gnomad AFR exome

AF:

0.000130

Gnomad AMR exome

AF:

0.000820

Gnomad ASJ exome

AF:

0.00568

Gnomad EAS exome

AF:

0.00

Gnomad SAS exome

AF:

0.00527

Gnomad FIN exome

AF:

0.00174

Gnomad NFE exome

AF:

0.00329

Gnomad OTH exome

AF:

0.00202

GnomAD4 exome

AF:

0.00274

AC:

3981

AN:

1454864

Hom.:

Cov.:

AF XY:

0.00278

AC XY:

2009

AN XY:

722532

show subpopulations

Gnomad4 AFR exome

AF:

0.000452

Gnomad4 AMR exome

AF:

0.000948

Gnomad4 ASJ exome

AF:

0.00443

Gnomad4 EAS exome

AF:

0.00

Gnomad4 SAS exome

AF:

0.00524

Gnomad4 FIN exome

AF:

0.00124

Gnomad4 NFE exome

AF:

0.00283

Gnomad4 OTH exome

AF:

0.00208

GnomAD4 genome

AF:

0.00198

AC:

302

AN:

152258

Hom.:

Cov.:

AF XY:

0.00216

AC XY:

161

AN XY:

74442

show subpopulations

Gnomad4 AFR

AF:

0.000385

Gnomad4 AMR

AF:

0.000719

Gnomad4 ASJ

AF:

0.00259

Gnomad4 EAS

AF:

0.00

Gnomad4 SAS

AF:

0.00580

Gnomad4 FIN

AF:

0.00179

Gnomad4 NFE

AF:

0.00310

Gnomad4 OTH

AF:

0.00189

Alfa

AF:

0.00287

Hom.:

Bravo

AF:

0.00172

TwinsUK

AF:

0.00189

AC:

ALSPAC

AF:

0.00285

AC:

ESP6500AA

AF:

0.000524

AC:

ESP6500EA

AF:

0.00230

AC:

ExAC

AF:

0.00245

AC:

296

Asia WGS

AF:

0.00289

AC:

AN:

3476

EpiCase

AF:

0.00295

EpiControl

AF:

0.00261

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:1Uncertain:8Benign:18

Revision: criteria provided, conflicting classifications

LINK: link

Submissions by phenotype

not specified

Benign:6

Likely benign, criteria provided, single submitter	clinical testing	Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine	Mar 30, 2015	p.Pro28158Ser in exon 288 of TTN: This variant is not expected to have clinical significance because it has been identified in 0.5% (77/15570) of South Asian ch romosomes and 0.3% (199/65938) European chromosomes by the Exome Aggregation Con sortium (ExAC, http://exac.broadinstitute.org; dbSNP rs72648247). -
Benign, no assertion criteria provided	clinical testing	Genome Diagnostics Laboratory, University Medical Center Utrecht	-	- -
Benign, no assertion criteria provided	clinical testing	Joint Genome Diagnostic Labs from Nijmegen and Maastricht, Radboudumc and MUMC+	-	- -
Likely benign, criteria provided, single submitter	clinical testing	Eurofins Ntd Llc (ga)	Jul 31, 2015	- -
Benign, criteria provided, single submitter	clinical testing	Women's Health and Genetics/Laboratory Corporation of America, LabCorp	Dec 04, 2020	Variant summary: TTN c.84472C>T (p.Pro28158Ser) results in a non-conservative amino acid change located in the A-band of the encoded protein sequence. Five of five in-silico tools predict a damaging effect of the variant on protein function. The variant allele was found at a frequency of 0.0027 in 245714 control chromosomes in the gnomAD database, including 3 homozygotes. The observed variant frequency is approximately 4 fold of the estimated maximal expected allele frequency for a pathogenic variant in TTN causing Cardiomyopathy phenotype (0.00063), strongly suggesting that the variant is benign. Co-occurrences with a pathogenic variant has been reported (MYBPC3 c.3628-41_3628-17del25), providing supporting evidence for a benign role. Eight clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar after 2014 without evidence for independent evaluation. Multiple laboratories reported the variant with conflicting assessments (benign/likely benign n=6, VUS n=2). Based on the evidence outlined above, the variant was classified as benign. -
Benign, no assertion criteria provided	clinical testing	Clinical Genetics, Academic Medical Center	-	- -

not provided

Benign:5

Likely benign, no assertion criteria provided	clinical testing	Diagnostic Laboratory, Department of Genetics, University Medical Center Groningen	-	- -
Likely benign, criteria provided, single submitter	research	Biesecker Lab/Clinical Genomics Section, National Institutes of Health	Jun 24, 2013	- -
Likely benign, no assertion criteria provided	clinical testing	Clinical Genetics DNA and cytogenetics Diagnostics Lab, Erasmus MC, Erasmus Medical Center	-	- -
Benign, criteria provided, single submitter	clinical testing	GeneDx	Apr 24, 2018	This variant is associated with the following publications: (PMID: 24503780) -
Likely benign, criteria provided, single submitter	clinical testing	CeGaT Center for Human Genetics Tuebingen	Aug 01, 2024	TTN: BS2 -

Early-onset myopathy with fatal cardiomyopathy

Uncertain:1Benign:1

Uncertain significance, criteria provided, single submitter	clinical testing	Illumina Laboratory Services, Illumina	Jun 14, 2016	- -
Likely benign, criteria provided, single submitter	clinical testing	Neuberg Centre For Genomic Medicine, NCGM	Mar 01, 2023	- -

Tip-toe gait

Pathogenic:1

Likely pathogenic, no assertion criteria provided

clinical testing

Practice for Gait Abnormalities, David Pomarino, Competency Network Toe Walking c/o Practice Pomarino

Myopathy refers to diseases that affect skeletal Muscles. These diseases attack muscle fibers, making muscles weak. Inherited myopathies are often caused by inheriting an abnormal gene mutation from a parent that causes the disease. Symptoms of congenital myopathies usually start at birth or in early childhood, but may not appear until the teen years or even later in adulthood. Congenital myopathies are somewhat unique compared with other inherited myopathies, as weakness typically affects all muscles and is often not progressive. Symptoms are: Muscle weakness, most commonly of upper arms and shoulders and thighs, muscle cramps, stiffness and spasms, fatigue with exertion and lack of energy. Our patients all walk on tiptoe, so they show similar symptoms. When we genetically test them with our toe walking panel, we find that around 90 per cent of them have a genetic variant that explains their toe walking. These can be assigned, for example, to the area of myopathies (such as variants of the COL6A3 gene), the area of hereditary neuropathies (such as variants of the KMT2C gene) or the area of metabolic diseases (such as variants of the PYGM gene). In a smaller group of patients with almost identical symptoms, no abnormality is found in the genes of our panel, but spastic paraplegia can be detected. In another small group of our toe walkers, no abnormalities can be detected in the genes analysed in our toe walking panel, nor do they suffer from spastic paraplegia, as is also the case with healthy children. In contrast to these, however, they show a tiptoe gait. These patients suffer from infantile cerebral palsy, in which toe walking can also be observed. -

Autosomal recessive limb-girdle muscular dystrophy type 2J

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Illumina Laboratory Services, Illumina

Jan 13, 2018

This variant was observed in the ICSL laboratory as part of a predisposition screen in an ostensibly healthy population. It had not been previously curated by ICSL or reported in the Human Gene Mutation Database (HGMD: prior to June 1st, 2018), and was therefore a candidate for classification through an automated scoring system. Utilizing variant allele frequency, disease prevalence and penetrance estimates, and inheritance mode, an automated score was calculated to assess if this variant is too frequent to cause the disease. Based on the score, this variant could not be ruled out of causing disease and therefore its association with disease required further investigation. A literature search was performed for the gene, cDNA change, and amino acid change (if applicable). No publications were found based on this search. This variant was therefore classified as a variant of unknown significance for this disease. -

Limb-girdle muscular dystrophy, recessive

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Illumina Laboratory Services, Illumina

Jun 14, 2016

- -

Hypertrophic cardiomyopathy

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Illumina Laboratory Services, Illumina

Jun 14, 2016

- -

Dilated cardiomyopathy 1G

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Illumina Laboratory Services, Illumina

Jan 13, 2018

Dilated Cardiomyopathy, Dominant

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Illumina Laboratory Services, Illumina

Jun 14, 2016

- -

Myopathy, myofibrillar, 9, with early respiratory failure

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Illumina Laboratory Services, Illumina

Jun 14, 2016

- -

Tibial muscular dystrophy

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Illumina Laboratory Services, Illumina

Jun 14, 2016

- -

TTN-related disorder

Benign:1

Likely benign, no assertion criteria provided

clinical testing

PreventionGenetics, part of Exact Sciences

Jun 13, 2019

This variant is classified as likely benign based on ACMG/AMP sequence variant interpretation guidelines (Richards et al. 2015 PMID: 25741868, with internal and published modifications). -

Cardiomyopathy

Benign:1

Benign, criteria provided, single submitter

clinical testing

CHEO Genetics Diagnostic Laboratory, Children's Hospital of Eastern Ontario

Oct 28, 2019

- -

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

Benign:1

Benign, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Jan 29, 2024

- -

Supraventricular tachycardia

Benign:1

Likely benign, criteria provided, single submitter

clinical testing

Center for Advanced Laboratory Medicine, UC San Diego Health, University of California San Diego

Oct 02, 2017

- -

Cardiovascular phenotype

Benign:1

Benign, criteria provided, single submitter

clinical testing

Ambry Genetics

May 08, 2023

This alteration is classified as benign based on a combination of the following: population frequency, intact protein function, lack of segregation with disease, co-occurrence, RNA analysis, in silico models, amino acid conservation, lack of disease association in case-control studies, and/or the mechanism of disease or impacted region is inconsistent with a known cause of pathogenicity. -

TTN-related myopathy

Benign:1

Likely benign, criteria provided, single submitter

clinical testing

Molecular Genetics, Royal Melbourne Hospital

May 05, 2023

South Asian population allele frequency is 0.5% (rs72648247, 159/30150 alleles, 1 homozygote in gnomAD v2.1) with a null REVEL score. Based on the classification scheme RMH Modified ACMG/AMP Guidelines v1.6.1, this variant is classified as LIKELY BENIGN. Following criteria are met: BS1 -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Pathogenic

0.98

BayesDel_addAF

Benign

-0.31

BayesDel_noAF

Benign

-0.21

CADD

Benign

DANN

Benign

0.91

Eigen

Pathogenic

1.0

Eigen_PC

Pathogenic

0.94

FATHMM_MKL

Pathogenic

0.99

LIST_S2

Uncertain

0.89

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

M_CAP

Benign

0.071

MetaRNN

Benign

0.0081

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

MetaSVM

Uncertain

0.36

MutationAssessor

Pathogenic

4.2

.;.;.;H;.;.;H

MutationTaster

Benign

1.0

D;D;D;D;D;D

PrimateAI

Uncertain

0.62

PROVEAN

Pathogenic

-5.8

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

REVEL

Uncertain

0.52

Sift

Uncertain

0.0050

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

Polyphen

1.0

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

Vest4

0.46

MVP

0.46

MPC

0.47

ClinPred

0.079

GERP RS

5.7

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