rs72648951

chr2-178729034-T-C

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.19004A>G(p.Asp6335Gly) variant causes a missense change. The variant allele was found at a frequency of 0.00166 in 1,612,910 control chromosomes in the GnomAD database, including 42 homozygotes. In-silico tool predicts 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. D6335N) has been classified as Uncertain significance.

• Frequency:
  • Genomes: 𝑓 0.0094 (20 hom., cov: 33)
  • Exomes 𝑓: 0.00086 (22 hom.)
• Consequence: TTN NM_001267550.2 missense
• Clinical Significance: Benign/Likely benign criteria provided, multiple submitters, no conflicts B:20
• Conservation: PhyloP100: 3.95

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 where missense usually causes diseases, TTN
• BP4: Computational evidence support a benign effect (MetaRNN=0.0041165054).
• BP6: Variant 2-178729034-T-C is Benign according to our data. Variant chr2-178729034-T-C is described in ClinVar as [Likely_benign]. Clinvar id is 46651.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr2-178729034-T-C is described in Lovd as [Benign]. Variant chr2-178729034-T-C is described in Lovd as [Likely_benign].
• BS1: Variant frequency is greater than expected in population afr. gnomad4 allele frequency = 0.00936 (1425/152232) while in subpopulation AFR AF= 0.0323 (1342/41556). AF 95% confidence interval is 0.0309. There are 20 homozygotes in gnomad4. There are 647 alleles in male gnomad4 subpopulation. This position pass quality control queck.
• BS2: High Homozygotes in GnomAd at 21 AD,AR gene

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
TTN	NM_001267550.2	c.19004A>G	p.Asp6335Gly	missense_variant	65/363	ENST00000589042.5

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
TTN	ENST00000589042.5	c.19004A>G	p.Asp6335Gly	missense_variant	65/363	5	NM_001267550.2	P1
TTN-AS1	ENST00000659121.1	n.503-5470T>C		intron_variant, non_coding_transcript_variant

Frequencies

GnomAD3 genomes AF: 0.00937 AC: 1426 AN: 152114 Hom.: 21 Cov.: 33

Gnomad AFR AF: 0.0324

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00354

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.000207

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00316

Gnomad NFE AF: 0.0000588

Gnomad OTH AF: 0.0110

GnomAD3 exomes AF: 0.00228 AC: 563 AN: 246512 Hom.: 12 AF XY: 0.00160 AC XY: 214 AN XY: 133768

Gnomad AFR exome AF: 0.0326

Gnomad AMR exome AF: 0.00131

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad SAS exome AF: 0.0000657

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.0000719

Gnomad OTH exome AF: 0.00134

GnomAD4 exome AF: 0.000863 AC: 1260 AN: 1460678 Hom.: 22 Cov.: 32 AF XY: 0.000723 AC XY: 525 AN XY: 726586

Gnomad4 AFR exome AF: 0.0305

Gnomad4 AMR exome AF: 0.00168

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.0000580

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.0000261

Gnomad4 OTH exome AF: 0.00214

GnomAD4 genome AF: 0.00936 AC: 1425 AN: 152232 Hom.: 20 Cov.: 33 AF XY: 0.00869 AC XY: 647 AN XY: 74428

Gnomad4 AFR AF: 0.0323

Gnomad4 AMR AF: 0.00353

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.000207

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.0000588

Gnomad4 OTH AF: 0.0109

Alfa AF: 0.00146 Hom.: 7

Bravo AF: 0.0106

ESP6500AA AF: 0.0280 AC: 104

ESP6500EA AF: 0.00 AC: 0

ExAC AF: 0.00292 AC: 353

Asia WGS AF: 0.000578 AC: 2 AN: 3476

EpiCase AF: 0.00

EpiControl AF: 0.0000596

ClinVar

Significance: Benign/Likely benign

Submissions summary: Benign:20

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not specified Benign:7

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	Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine	Mar 06, 2013	Asp5091Gly in exon 62 of TTN: This variant is not expected to have clinical sign ificance because it has been identified in 2.8% (104/3716) of African American c hromosomes from a broad population by the NHLBI Exome Sequencing Project (http:/ /evs.gs.washington.edu/EVS; dbSNP rs72648951). -
Benign, criteria provided, single submitter	clinical testing	Genetic Services Laboratory, University of Chicago	Aug 26, 2013	- -
Benign, criteria provided, single submitter	clinical testing	GeneDx	Apr 07, 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. -
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	Clinical Genetics, Academic Medical Center	-	- -
Benign, criteria provided, single submitter	clinical testing	Women's Health and Genetics/Laboratory Corporation of America, LabCorp	Nov 06, 2019	Variant summary: TTN c.15272A>G (p.Asp5091Gly) results in a non-conservative amino acid change located in the I-band region of the encoded protein sequence. Three of five in-silico tools predict a benign effect of the variant on protein function. The variant allele was found at a frequency of 0.0023 in 246512 control chromosomes, predominantly at a frequency of 0.033 within the African or African-American subpopulation in the gnomAD database (exome dataset), including 12 homozygotes. The observed variant frequency within African or African-American control individuals in the gnomAD database is approximately 50-fold the estimated maximal expected allele frequency for a pathogenic variant in TTN causing Cardiomyopathy phenotype (0.00063), strongly suggesting that the variant is a benign polymorphism found primarily in populations of African or African-American origin. To our knowledge, no occurrence of c.15272A>G in individuals affected with Cardiomyopathy and no experimental evidence demonstrating an impact on protein function have been reported. Co-occurrence with another pathogenic variant has been reported (TTR c.424G>A, p.Val142Ile; internal sample), providing supporting evidence for a benign role. Three clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar after 2014 without evidence for independent evaluation. All laboratories classified the variant as benign/likely benign. Based on the evidence outlined above, the variant was classified as benign. -

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	- -
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. -

not provided Benign:2

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	ARUP Laboratories, Molecular Genetics and Genomics, ARUP Laboratories	Dec 21, 2022	- -

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. -

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. -

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

- -

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 09, 2016

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.10
BayesDel_addAF	Benign	-0.46	T
BayesDel_noAF	Benign	-0.40
Cadd	Benign	23
Dann	Benign	0.94
Eigen	Benign	-0.063
Eigen_PC	Benign	0.13
FATHMM_MKL	Uncertain	0.95	D
LIST_S2	Benign	0.66	T;T;.;T
MetaRNN	Benign	0.0041	T;T;T;T
MetaSVM	Benign	-1.1	T
MutationTaster	Benign	1.0	D;D;D;N;N;N
PrimateAI	Benign	0.44	T
PROVEAN	Uncertain	-2.4	N;.;.;.
REVEL	Benign	0.10
Sift	Benign	0.63	T;.;.;.
Polyphen		0.0010	.;.;B;B
Vest4		0.42
MVP		0.11
MPC		0.11
ClinPred		0.013	T
GERP RS		4.8

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.40		Details are displayed if max score is > 0.2
DS_DG_spliceai		0.40		Position offset: 1

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

LitVar

Other links and lift over

dbSNP: rs72648951; hg19: chr2-179593761; COSMIC: COSV99045627; COSMIC: COSV99045627;