rs72648230

Positions:

• chr2-178557491-G-T

Variant summary

Our verdict is Likely benign. Variant got -6 ACMG points: 0P and 6B. BP4_Strong BP6 BP7

The NM_001267550.2(TTN):​c.87771C>A​(p.Gly29257=) variant causes a synonymous change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000762 in 1,613,788 control chromosomes in the GnomAD database, with no homozygous occurrence. 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 0.00014 (0 hom., cov: 33)
  • Exomes 𝑓: 0.000069 (0 hom.)
• Consequence: TTN NM_001267550.2 synonymous
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:1 B:8
• Conservation: PhyloP100: 1.32

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 Likely_benign. Variant got -6 ACMG points.

• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.62).
• BP6: Variant 2-178557491-G-T is Benign according to our data. Variant chr2-178557491-G-T is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 378826.We mark this variant Likely_benign, oryginal submissions are: {Likely_benign=5, Uncertain_significance=1, Benign=1}. Variant chr2-178557491-G-T is described in Lovd as [Likely_benign].
• BP7: Synonymous conserved (PhyloP=1.32 with no splicing effect.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
TTN	NM_001267550.2	c.87771C>A	p.Gly29257=	synonymous_variant	329/363	ENST00000589042.5
TTN-AS1	NR_038272.1	n.2043+15130G>T		intron_variant, non_coding_transcript_variant

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
TTN	ENST00000589042.5	c.87771C>A	p.Gly29257=	synonymous_variant	329/363	5	NM_001267550.2	P1
	ENST00000624360.1	n.2931G>T		non_coding_transcript_exon_variant	1/1
TTN-AS1	ENST00000659121.1	n.416+33855G>T		intron_variant, non_coding_transcript_variant

Frequencies

GnomAD3 genomes AF: 0.000145 AC: 22 AN: 152192 Hom.: 0 Cov.: 33

Gnomad AFR AF: 0.000193

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.0000655

Gnomad ASJ AF: 0.000288

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.000162

Gnomad OTH AF: 0.000478

GnomAD3 exomes AF: 0.000105 AC: 26 AN: 248580 Hom.: 0 AF XY: 0.000104 AC XY: 14 AN XY: 134834

Gnomad AFR exome AF: 0.000387

Gnomad AMR exome AF: 0.0000580

Gnomad ASJ exome AF: 0.0000996

Gnomad EAS exome AF: 0.00

Gnomad SAS exome AF: 0.0000654

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.000133

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.0000691 AC: 101 AN: 1461596 Hom.: 0 Cov.: 33 AF XY: 0.0000770 AC XY: 56 AN XY: 727080

Gnomad4 AFR exome AF: 0.000239

Gnomad4 AMR exome AF: 0.0000671

Gnomad4 ASJ exome AF: 0.0000383

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.0000927

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.0000612

Gnomad4 OTH exome AF: 0.000116

GnomAD4 genome AF: 0.000145 AC: 22 AN: 152192 Hom.: 0 Cov.: 33 AF XY: 0.000135 AC XY: 10 AN XY: 74340

Gnomad4 AFR AF: 0.000193

Gnomad4 AMR AF: 0.0000655

Gnomad4 ASJ AF: 0.000288

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.000162

Gnomad4 OTH AF: 0.000478

Alfa AF: 0.000116 Hom.: 0

Bravo AF: 0.000132

EpiCase AF: 0.000218

EpiControl AF: 0.000356

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:1 Benign:8

Revision: criteria provided, conflicting classifications

Submissions by phenotype

not provided Uncertain:1 Benign:3

Uncertain significance, criteria provided, single submitter	clinical testing	Eurofins Ntd Llc (ga)	Jan 19, 2017	- -
Likely benign, criteria provided, single submitter	clinical testing	CeGaT Center for Human Genetics Tuebingen	Jul 01, 2024	TTN: BP4, BP7 -
Likely benign, no assertion criteria provided	clinical testing	Clinical Genetics DNA and cytogenetics Diagnostics Lab, Erasmus MC, Erasmus Medical Center	-	- -
Likely benign, criteria provided, single submitter	clinical testing	ARUP Laboratories, Molecular Genetics and Genomics, ARUP Laboratories	Mar 25, 2018	The c.80067C>A p.Gly26689Gly variant (rs72648230, ClinVar variant ID 378826) does not alter the amino acid sequence of the TTN protein and computational splice site prediction algorithms do not predict a change in the nearest splice site or creation of a cryptic splice site. This variant is listed in the genome Aggregation Database (gnomAD) with an African population frequency of 0.03% (identified on 7 out of 24,018 chromosomes), and evidence suggests that the vast majority of rare non-truncating TTN variants do not contribute to the clinical outcome of DCM (Begay 2015). Given the available evidence, the c.80067C>A variant is likely to be benign. -

not specified Benign:3

Likely benign, criteria provided, single submitter	clinical testing	Women's Health and Genetics/Laboratory Corporation of America, LabCorp	Oct 29, 2023	- -
Benign, no assertion criteria provided	clinical testing	Clinical Genetics, Academic Medical Center	-	- -
Benign, criteria provided, single submitter	clinical testing	GeneDx	Jul 28, 2015	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. -

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

Likely benign, criteria provided, single submitter

clinical testing

Invitae

Jan 24, 2024

- -

Cardiovascular phenotype Benign:1

Likely benign, criteria provided, single submitter

clinical testing

Ambry Genetics

Nov 27, 2019

This alteration is classified as likely 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	-0.62
CADD	Benign	15
DANN	Benign	0.78

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: rs72648230; hg19: chr2-179422218; COSMIC: COSV60103527;