rs199598302

chr2-178587335-G-A

Variant summary

Our verdict is Benign. Variant got -21 ACMG points: 0P and 21B. BP4_Strong BP6_Very_Strong BP7 BS1 BS2

The NM_001267550.2(TTN):c.63876C>T(p.Asn21292=) variant causes a synonymous change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00169 in 1,612,614 control chromosomes in the GnomAD database, including 59 homozygotes. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Likely benign (★★).

• Frequency:
  • Genomes: 𝑓 0.0014 (4 hom., cov: 32)
  • Exomes 𝑓: 0.0017 (55 hom.)
• Consequence: TTN NM_001267550.2 synonymous
• Clinical Significance: Benign/Likely benign criteria provided, multiple submitters, no conflicts B:20
• Conservation: PhyloP100: 2.15

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 -21 ACMG points.

• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.5).
• BP6: Variant 2-178587335-G-A is Benign according to our data. Variant chr2-178587335-G-A is described in ClinVar as [Likely_benign]. Clinvar id is 47199.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr2-178587335-G-A is described in Lovd as [Benign]. Variant chr2-178587335-G-A is described in Lovd as [Likely_benign].
• BP7: Synonymous conserved (PhyloP=2.14 with no splicing effect.
• BS1: Variant frequency is greater than expected in population sas. gnomad4 allele frequency = 0.00142 (216/152038) while in subpopulation SAS AF= 0.0274 (132/4816). AF 95% confidence interval is 0.0236. There are 4 homozygotes in gnomad4. There are 130 alleles in male gnomad4 subpopulation. This position pass quality control queck.
• BS2: High Homozygotes in GnomAd at 4 AD,AR gene

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
TTN	NM_001267550.2	c.63876C>T	p.Asn21292=	synonymous_variant	307/363	ENST00000589042.5
TTN-AS1	NR_038272.1	n.3188+2342G>A		intron_variant, non_coding_transcript_variant

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
TTN	ENST00000589042.5	c.63876C>T	p.Asn21292=	synonymous_variant	307/363	5	NM_001267550.2	P1
TTN-AS1	ENST00000659121.1	n.417-10261G>A		intron_variant, non_coding_transcript_variant

Frequencies

GnomAD3 genomes AF: 0.00138 AC: 209 AN: 151920 Hom.: 4 Cov.: 32

Gnomad AFR AF: 0.00147

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.000459

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.0276

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.000118

Gnomad OTH AF: 0.00

GnomAD3 exomes AF: 0.00348 AC: 858 AN: 246692 Hom.: 15 AF XY: 0.00468 AC XY: 626 AN XY: 133848

Gnomad AFR exome AF: 0.00156

Gnomad AMR exome AF: 0.000204

Gnomad ASJ exome AF: 0.000200

Gnomad EAS exome AF: 0.000114

Gnomad SAS exome AF: 0.0264

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.0000808

Gnomad OTH exome AF: 0.00117

GnomAD4 exome AF: 0.00172 AC: 2507 AN: 1460576 Hom.: 55 Cov.: 33 AF XY: 0.00246 AC XY: 1784 AN XY: 726570

Gnomad4 AFR exome AF: 0.00138

Gnomad4 AMR exome AF: 0.000224

Gnomad4 ASJ exome AF: 0.0000766

Gnomad4 EAS exome AF: 0.000127

Gnomad4 SAS exome AF: 0.0260

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.0000729

Gnomad4 OTH exome AF: 0.00196

GnomAD4 genome AF: 0.00142 AC: 216 AN: 152038 Hom.: 4 Cov.: 32 AF XY: 0.00175 AC XY: 130 AN XY: 74302

Gnomad4 AFR AF: 0.00147

Gnomad4 AMR AF: 0.000458

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.0274

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.000118

Gnomad4 OTH AF: 0.00379

Alfa AF: 0.000403 Hom.: 0

Bravo AF: 0.000763

Asia WGS AF: 0.0230 AC: 79 AN: 3478

EpiCase AF: 0.000109

EpiControl AF: 0.00

ClinVar

Significance: Benign/Likely benign

Submissions summary: Benign:20

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not specified Benign:6

Benign, no assertion criteria provided	clinical testing	Clinical Genetics, Academic Medical Center	-	- -
Benign, criteria provided, single submitter	clinical testing	Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine	Nov 20, 2014	p.Asn18724Asn in exon 256 of TTN: This variant is not expected to have clinical significance because it has been identified in 2.9% (469/16064) of South Asian c hromosomes by the Exome Aggregation Consortium (ExAC, http://exac.broadinstitute .org). -
Benign, criteria provided, single submitter	clinical testing	Women's Health and Genetics/Laboratory Corporation of America, LabCorp	Aug 19, 2023	- -
Benign, criteria provided, single submitter	clinical testing	Athena Diagnostics	Sep 25, 2019	- -
Benign, criteria provided, single submitter	clinical testing	GeneDx	Sep 30, 2014	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. -
Likely benign, criteria provided, single submitter	clinical testing	Genetic Services Laboratory, University of Chicago	Apr 04, 2015	- -

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

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

Early-onset myopathy with fatal cardiomyopathy Benign:2

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

not provided Benign:2

Likely benign, no assertion criteria provided	clinical testing	Clinical Genetics DNA and cytogenetics Diagnostics Lab, Erasmus MC, Erasmus Medical Center	-	- -
Likely benign, no assertion criteria provided	clinical testing	Diagnostic Laboratory, Department of Genetics, University Medical Center Groningen	-	- -

Tibial muscular dystrophy Benign:2

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. -
Benign, criteria provided, single submitter	clinical testing	Genome-Nilou Lab	Sep 10, 2021	- -

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

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. -
Benign, criteria provided, single submitter	clinical testing	Genome-Nilou Lab	Sep 10, 2021	- -

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

Benign, criteria provided, single submitter

clinical testing

Invitae

Jan 24, 2024

- -

Cardiomyopathy Benign:1

Benign, criteria provided, single submitter

clinical testing

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

Jan 06, 2016

- -

Dilated cardiomyopathy 1G Benign:1

Likely 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 likely benign is not then subjected to further curation. The score for this variant resulted in a classification of likely benign for this disease. -

Cardiovascular phenotype Benign:1

Benign, criteria provided, single submitter

clinical testing

Ambry Genetics

Mar 29, 2019

This alteration is classified as benign based on a combination of the following: seen in unaffected individuals, 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
BayesDel_noAF	Benign	-0.50
Cadd	Benign	0.64
Dann	Benign	0.87

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: rs199598302; hg19: chr2-179452062; COSMIC: COSV100601173; COSMIC: COSV100601173;