2-178530827-G-A

Position:

• chr2-178530827-G-A

Variant summary

Our verdict is Benign. Variant got -19 ACMG points: 1P and 20B. PP2 BP4_Strong BP6_Very_Strong BS1 BS2

The NM_001267550.2(TTN):​c.105788C>T​(p.Ala35263Val) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0135 in 1,613,782 control chromosomes in the GnomAD database, including 188 homozygotes. In-silico tool predicts a benign outcome for this variant. 15/18 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Likely benign (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. A35263F) has been classified as Benign.

• Frequency:
  • Genomes: 𝑓 0.010 (23 hom., cov: 33)
  • Exomes 𝑓: 0.014 (165 hom.)
• Consequence: TTN NM_001267550.2 missense
• Clinical Significance: Benign/Likely benign criteria provided, multiple submitters, no conflicts B:24
• Conservation: PhyloP100: 1.52

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 Benign. Variant got -19 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=0.0022972524).
• BP6: Variant 2-178530827-G-A is Benign according to our data. Variant chr2-178530827-G-A is described in ClinVar as [Likely_benign]. Clinvar id is 47702.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr2-178530827-G-A is described in Lovd as [Benign]. Variant chr2-178530827-G-A is described in Lovd as [Likely_benign].
• BS1: Variant frequency is greater than expected in population nfe. gnomad4 allele frequency = 0.0103 (1567/152102) while in subpopulation NFE AF= 0.0155 (1056/68002). AF 95% confidence interval is 0.0148. There are 23 homozygotes in gnomad4. There are 754 alleles in male gnomad4 subpopulation. Median coverage is 33. This position pass quality control queck.
• BS2: High Homozygotes in GnomAd4 at 23 AD,AR gene

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
TTN	NM_001267550.2	c.105788C>T	p.Ala35263Val	missense_variant	358/363	ENST00000589042.5	NP_001254479.2
TTN-AS1	NR_038272.1	n.220-4905G>A		intron_variant, non_coding_transcript_variant

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
TTN	ENST00000589042.5	c.105788C>T	p.Ala35263Val	missense_variant	358/363	5	NM_001267550.2	ENSP00000467141	P1
TTN-AS1	ENST00000659121.1	n.416+7191G>A		intron_variant, non_coding_transcript_variant

Frequencies

GnomAD3 genomes AF: 0.0103 AC: 1567 AN: 151984 Hom.: 23 Cov.: 33

Gnomad AFR AF: 0.00251

Gnomad AMI AF: 0.00548

Gnomad AMR AF: 0.00688

Gnomad ASJ AF: 0.00576

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.000415

Gnomad FIN AF: 0.0238

Gnomad MID AF: 0.0253

Gnomad NFE AF: 0.0155

Gnomad OTH AF: 0.00765

GnomAD3 exomes AF: 0.0109 AC: 2724 AN: 249062 Hom.: 24 AF XY: 0.0107 AC XY: 1450 AN XY: 135100

Gnomad AFR exome AF: 0.00233

Gnomad AMR exome AF: 0.00461

Gnomad ASJ exome AF: 0.00596

Gnomad EAS exome AF: 0.00

Gnomad SAS exome AF: 0.00154

Gnomad FIN exome AF: 0.0242

Gnomad NFE exome AF: 0.0163

Gnomad OTH exome AF: 0.00976

GnomAD4 exome AF: 0.0138 AC: 20216 AN: 1461680 Hom.: 165 Cov.: 33 AF XY: 0.0134 AC XY: 9777 AN XY: 727122

Gnomad4 AFR exome AF: 0.00173

Gnomad4 AMR exome AF: 0.00472

Gnomad4 ASJ exome AF: 0.00647

Gnomad4 EAS exome AF: 0.0000252

Gnomad4 SAS exome AF: 0.00133

Gnomad4 FIN exome AF: 0.0246

Gnomad4 NFE exome AF: 0.0158

Gnomad4 OTH exome AF: 0.0115

GnomAD4 genome AF: 0.0103 AC: 1567 AN: 152102 Hom.: 23 Cov.: 33 AF XY: 0.0101 AC XY: 754 AN XY: 74336

Gnomad4 AFR AF: 0.00251

Gnomad4 AMR AF: 0.00687

Gnomad4 ASJ AF: 0.00576

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.000416

Gnomad4 FIN AF: 0.0238

Gnomad4 NFE AF: 0.0155

Gnomad4 OTH AF: 0.00757

Alfa AF: 0.00462 Hom.: 11

Bravo AF: 0.00868

TwinsUK AF: 0.0148 AC: 55

ALSPAC AF: 0.0153 AC: 59

ESP6500AA AF: 0.00210 AC: 8

ESP6500EA AF: 0.0143 AC: 118

ExAC AF: 0.0114 AC: 1377

Asia WGS AF: 0.00144 AC: 5 AN: 3478

EpiCase AF: 0.0137

EpiControl AF: 0.0148

ClinVar

Significance: Benign/Likely benign

Submissions summary: Benign:24

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not specified Benign:8

Benign, no assertion criteria provided	clinical testing	Clinical Genetics, Academic Medical Center	-	- -
Likely benign, no assertion criteria provided	clinical testing	Genetic Services Laboratory, University of Chicago	-	Likely benign based on allele frequency in 1000 Genomes Project or ESP global frequency and its presence in a patient with a rare or unrelated disease phenotype. NOT Sanger confirmed. -
Benign, criteria provided, single submitter	clinical testing	Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine	Mar 26, 2012	Ala32695Ser & Ala32695Val in exon 307 of TTN: These variants are not expected to have clinical significance because they have been independently described in th e same populations, at the same frequency, and alter adjacent bases and may repr esent a single allele (Ala32695Phe). These variants have each been identified in 1.3% (89/6634) of European American chromosomes from a broad population by the NHLBI Exome Sequencing Project (http://evs.gs.washington.edu/EVS; dbSNP rs672545 37 & rs66961115). -
Benign, criteria provided, single submitter	research	Biesecker Lab/Clinical Genomics Section, National Institutes of Health	Jun 24, 2013	- -
Benign, no assertion criteria provided	clinical testing	Genome Diagnostics Laboratory, University Medical Center Utrecht	-	- -
Benign, criteria provided, single submitter	clinical testing	PreventionGenetics, part of Exact Sciences	-	- -
Benign, no assertion criteria provided	clinical testing	Joint Genome Diagnostic Labs from Nijmegen and Maastricht, Radboudumc and MUMC+	-	- -
Benign, criteria provided, single submitter	clinical testing	GeneDx	Oct 21, 2012	This variant is considered likely benign or benign based on one or more of the following criteria: it is a conservative change, it occurs at a poorly conserved position in the protein, it is predicted to be benign by multiple in silico algorithms, and/or has population frequency not consistent with disease. -

not provided Benign:4

Benign, criteria provided, single submitter	clinical testing	ARUP Laboratories, Molecular Genetics and Genomics, ARUP Laboratories	Nov 07, 2023	- -
Likely benign, no assertion criteria provided	clinical testing	Diagnostic Laboratory, Department of Genetics, University Medical Center Groningen	-	- -
Likely benign, no assertion criteria provided	clinical testing	Laboratory of Diagnostic Genome Analysis, Leiden University Medical Center (LUMC)	-	- -
Likely benign, criteria provided, single submitter	not provided	Breakthrough Genomics, Breakthrough Genomics	-	- -

Autosomal recessive limb-girdle muscular dystrophy type 2J Benign:2

Benign, criteria provided, single submitter	clinical testing	Genome-Nilou Lab	Sep 10, 2021	- -
Likely benign, 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 and internal cut-off values, a variant classified as likely benign is not then subjected to further curation. The score for this variant resulted in a classification of likely benign for this disease. -

Early-onset myopathy with fatal cardiomyopathy Benign:2

Benign, criteria provided, single submitter	clinical testing	Genome-Nilou Lab	Sep 10, 2021	- -
Likely benign, 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 and internal cut-off values, a variant classified as likely benign is not then subjected to further curation. The score for this variant resulted in a classification of likely benign for this disease. -

Myopathy, myofibrillar, 9, with early respiratory failure Benign:2

Benign, criteria provided, single submitter	clinical testing	Genome-Nilou Lab	Sep 10, 2021	- -
Benign, 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 and internal cut-off values, a variant classified as benign is not then subjected to further curation. The score for this variant resulted in a classification of benign for this disease. -

Tibial muscular dystrophy Benign:2

Benign, criteria provided, single submitter	clinical testing	Genome-Nilou Lab	Sep 10, 2021	- -
Benign, 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 and internal cut-off values, a variant classified as benign is not then subjected to further curation. The score for this variant resulted in a classification of benign for this disease. -

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 06, 2024

- -

Dilated cardiomyopathy 1G Benign:1

Likely benign, 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 and internal cut-off values, a variant classified as likely benign is not then subjected to further curation. The score for this variant resulted in a classification of likely benign for this disease. -

Cardiomyopathy Benign:1

Benign, criteria provided, single submitter

clinical testing

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

Nov 18, 2022

- -

Cardiovascular phenotype Benign:1

Likely benign, criteria provided, single submitter

clinical testing

Ambry Genetics

Nov 28, 2012

This alteration is classified as likely 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. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.089
BayesDel_addAF	Benign	-0.48	T
BayesDel_noAF	Benign	-0.44
CADD	Benign	8.9
DANN	Benign	0.97
Eigen	Benign	-0.28
Eigen_PC	Benign	-0.12
FATHMM_MKL	Uncertain	0.78	D
LIST_S2	Benign	0.74	T;T;T;.;T;T;T
MetaRNN	Benign	0.0023	T;T;T;T;T;T;T
MetaSVM	Benign	-0.94	T
MutationAssessor	Benign	0.90	.;.;.;L;.;.;L
MutationTaster	Benign	0.93	N;N;N;N;N;N
PrimateAI	Benign	0.31	T
PROVEAN	Benign	-1.5	N;N;.;.;N;N;.
REVEL	Benign	0.072
Sift	Benign	0.26	T;T;.;.;T;T;.
Polyphen		0.0	.;.;.;B;.;.;B
Vest4		0.077
MPC		0.083
ClinPred		0.0080	T
GERP RS		4.1
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.2

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: rs66961115; hg19: chr2-179395554;