rs146181116

chr2-178555065-G-A

Variant summary

Our verdict is Benign. Variant got -8 ACMG points: 1P and 9B. PP2 BP4_Strong BP6 BS1

The NM_001267550.2(TTN):c.88394C>T(p.Ser29465Phe) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00376 in 1,613,780 control chromosomes in the GnomAD database, including 19 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 0.0033 (0 hom., cov: 33)
  • Exomes 𝑓: 0.0038 (19 hom.)
• Consequence: TTN NM_001267550.2 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:3 B:22
• Conservation: PhyloP100: 2.18

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]

(HGNC:):

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 -8 ACMG points.

• PP2: Missense variant where missense usually causes diseases, TTN
• BP4: Computational evidence support a benign effect (MetaRNN=0.008737415).
• BP6: Variant 2-178555065-G-A is Benign according to our data. Variant chr2-178555065-G-A is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 47477.We mark this variant Likely_benign, oryginal submissions are: {Likely_benign=7, Uncertain_significance=3, Benign=9}. Variant chr2-178555065-G-A is described in Lovd as [Benign]. Variant chr2-178555065-G-A is described in Lovd as [Likely_benign].
• BS1: Variant frequency is greater than expected in population nfe. gnomad4 allele frequency = 0.00325 (495/152256) while in subpopulation NFE AF= 0.00556 (378/68010). AF 95% confidence interval is 0.0051. There are 0 homozygotes in gnomad4. There are 228 alleles in male gnomad4 subpopulation. This position pass quality control queck.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
TTN	NM_001267550.2	c.88394C>T	p.Ser29465Phe	missense_variant	331/363	ENST00000589042.5
TTN-AS1	NR_038272.1	n.2043+12704G>A		intron_variant, non_coding_transcript_variant

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
TTN	ENST00000589042.5	c.88394C>T	p.Ser29465Phe	missense_variant	331/363	5	NM_001267550.2	P1
	ENST00000624360.1	n.505G>A		non_coding_transcript_exon_variant	1/1
TTN-AS1	ENST00000659121.1	n.416+31429G>A		intron_variant, non_coding_transcript_variant

Frequencies

GnomAD3 genomes AF: 0.00325 AC: 495 AN: 152138 Hom.: 0 Cov.: 33

Gnomad AFR AF: 0.000772

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00144

Gnomad ASJ AF: 0.00115

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.000207

Gnomad FIN AF: 0.00519

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.00556

Gnomad OTH AF: 0.00144

GnomAD3 exomes AF: 0.00293 AC: 727 AN: 248266 Hom.: 1 AF XY: 0.00299 AC XY: 403 AN XY: 134654

Gnomad AFR exome AF: 0.000387

Gnomad AMR exome AF: 0.00128

Gnomad ASJ exome AF: 0.00209

Gnomad EAS exome AF: 0.00

Gnomad SAS exome AF: 0.000196

Gnomad FIN exome AF: 0.00645

Gnomad NFE exome AF: 0.00440

Gnomad OTH exome AF: 0.00282

GnomAD4 exome AF: 0.00381 AC: 5565 AN: 1461524 Hom.: 19 Cov.: 32 AF XY: 0.00378 AC XY: 2748 AN XY: 727050

Gnomad4 AFR exome AF: 0.000388

Gnomad4 AMR exome AF: 0.00134

Gnomad4 ASJ exome AF: 0.00203

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.000209

Gnomad4 FIN exome AF: 0.00706

Gnomad4 NFE exome AF: 0.00440

Gnomad4 OTH exome AF: 0.00249

GnomAD4 genome AF: 0.00325 AC: 495 AN: 152256 Hom.: 0 Cov.: 33 AF XY: 0.00306 AC XY: 228 AN XY: 74436

Gnomad4 AFR AF: 0.000770

Gnomad4 AMR AF: 0.00144

Gnomad4 ASJ AF: 0.00115

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.000207

Gnomad4 FIN AF: 0.00519

Gnomad4 NFE AF: 0.00556

Gnomad4 OTH AF: 0.00142

Alfa AF: 0.00453 Hom.: 5

Bravo AF: 0.00240

TwinsUK AF: 0.00378 AC: 14

ALSPAC AF: 0.00389 AC: 15

ESP6500AA AF: 0.00107 AC: 4

ESP6500EA AF: 0.00449 AC: 37

ExAC AF: 0.00271 AC: 328

EpiCase AF: 0.00447

EpiControl AF: 0.00350

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:3 Benign:22

Revision: criteria provided, conflicting classifications

Submissions by phenotype

not specified Benign:10

Benign, criteria provided, single submitter	research	Biesecker Lab/Clinical Genomics Section, National Institutes of Health	Jun 24, 2013	- -
Likely benign, criteria provided, single submitter	clinical testing	Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine	Jul 21, 2017	p.Ser26897Phe in exon 280 of TTN: This variant is not expected to have clinical significance because it has been identified in 0.6% (163/25786) of Finnish chrom osomes by the Genome Aggregation Database (gnomAD, http://gnomad.broadinstitute. org; dbSNP rs146181116) -
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 20, 2015	- -
Likely benign, criteria provided, single submitter	clinical testing	PreventionGenetics, part of Exact Sciences	-	- -
Likely benign, criteria provided, single submitter	clinical testing	Genetic Services Laboratory, University of Chicago	Aug 26, 2016	- -
Likely benign, criteria provided, single submitter	clinical testing	Women's Health and Genetics/Laboratory Corporation of America, LabCorp	Jan 14, 2021	Variant summary: TTN c.80690C>T (p.Ser26897Phe) results in a non-conservative amino acid change located in the A-band region of the encoded protein sequence. Three of five in-silico tools predict a damaging effect of the variant on protein function. The variant allele was found at a frequency of 0.0029 in 248266 control chromosomes in the gnomAD database, including 1 homozygotes. The observed variant frequency is approximately 4.68 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. c.80690C>T has been reported in the literature in individuals affected with Cardiomyopathy without strong evidence for causality (e.g. Forleo_2017). These reports do not provide unequivocal conclusions about association of the variant with Cardiomyopathy. Co-occurrence with another pathogenic variant has been reported ( MYH7 c.1207C>T, p.Arg403Trp- internal sample), providing supporting evidence for a benign role. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. Twelve clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar after 2014 without evidence for independent evaluation, citing the variant as likely benign/benign (n=10), and uncertain significance (n=2). Based on the evidence outlined above, the variant was classified as likely benign. -
Benign, no assertion criteria provided	clinical testing	Clinical Genetics DNA and cytogenetics Diagnostics Lab, Erasmus MC, Erasmus Medical Center	-	- -
Benign, no assertion criteria provided	clinical testing	Genome Diagnostics Laboratory, University Medical Center Utrecht	-	- -
Benign, no assertion criteria provided	clinical testing	Clinical Genetics, Academic Medical Center	-	- -

not provided Benign:6

Benign, criteria provided, single submitter	clinical testing	GeneDx	Apr 06, 2020	This variant is associated with the following publications: (PMID: 23396983) -
Likely benign, no assertion criteria provided	clinical testing	Laboratory of Diagnostic Genome Analysis, Leiden University Medical Center (LUMC)	-	- -
Benign, criteria provided, single submitter	clinical testing	Athena Diagnostics	Aug 14, 2019	- -
Likely benign, criteria provided, single submitter	clinical testing	CeGaT Center for Human Genetics Tuebingen	Mar 01, 2024	TTN: BS2 -
Likely benign, no assertion criteria provided	clinical testing	Diagnostic Laboratory, Department of Genetics, University Medical Center Groningen	-	- -
Benign, criteria provided, single submitter	clinical testing	ARUP Laboratories, Molecular Genetics and Genomics, ARUP Laboratories	Aug 24, 2023	- -

Autosomal recessive limb-girdle muscular dystrophy type 2J Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Illumina Laboratory Services, Illumina

Jan 12, 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. -

Dilated cardiomyopathy 1G Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Illumina Laboratory Services, Illumina

Jan 12, 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. -

Early-onset myopathy with fatal cardiomyopathy Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Illumina Laboratory Services, Illumina

Jan 12, 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. -

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

Benign, criteria provided, single submitter

clinical testing

Invitae

Feb 01, 2024

- -

Cardiomyopathy Benign:1

Benign, criteria provided, single submitter

clinical testing

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

Jan 07, 2020

- -

Hypertrophic cardiomyopathy;C0349788:Arrhythmogenic right ventricular cardiomyopathy Benign:1

Benign, criteria provided, single submitter

clinical testing

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

Apr 01, 2019

- -

Tibial muscular dystrophy Benign:1

Benign, criteria provided, single submitter

clinical testing

Illumina Laboratory Services, Illumina

Jan 12, 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. -

Myopathy, myofibrillar, 9, with early respiratory failure Benign:1

Benign, criteria provided, single submitter

clinical testing

Illumina Laboratory Services, Illumina

Jan 12, 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. -

Cardiovascular phenotype Benign:1

Likely benign, criteria provided, single submitter

clinical testing

Ambry Genetics

Nov 25, 2013

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	0.15
BayesDel_addAF	Benign	-0.36	T
BayesDel_noAF	Benign	-0.28
Cadd	Benign	21
Dann	Uncertain	0.98
Eigen	Uncertain	0.62
Eigen_PC	Uncertain	0.65
FATHMM_MKL	Uncertain	0.92	D
LIST_S2	Uncertain	0.91	D;D;D;.;D;D;D
M_CAP	Benign	0.042	D
MetaRNN	Benign	0.0087	T;T;T;T;T;T;T
MetaSVM	Benign	-0.36	T
MutationTaster	Benign	1.0	D;D;D;D;D;D
PrimateAI	Uncertain	0.52	T
PROVEAN	Uncertain	-3.7	D;D;.;.;D;D;.
REVEL	Uncertain	0.33
Sift	Benign	0.55	T;T;.;.;T;T;.
Polyphen		0.99	.;.;.;D;.;.;D
Vest4		0.49
MVP		0.53
MPC		0.35
ClinPred		0.030	T
GERP RS		5.7

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.010		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: rs146181116; hg19: chr2-179419792;