rs754717390

Variant summary

Our verdict is Uncertain significance. Variant got 2 ACMG points: 2P and 0B. PP3_Moderate

The NM_001267550.2(TTN):c.55432+5G>C variant causes a splice donor 5th base, intron change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.0000113 in 1,589,950 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 2/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).

Frequency

Genomes: 𝑓 0.000026 ( 0 hom., cov: 32)

Exomes 𝑓: 0.0000097 ( 0 hom. )

Consequence

TTN
NM_001267550.2 splice_donor_5th_base, intron

Scores

Splicing: ADA: 0.9998

Clinical Significance

Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:1U:8O:1

Conservation

PhyloP100: 7.45

Variant links:

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 links:

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]

TTN-AS1 links:

Genome browser will be placed here

ACMG classification

Classification made for transcript

Verdict is Uncertain_significance. Variant got 2 ACMG points.

PP3

Splicing scoreres supports a deletorius effect: Scorers claiming Pathogenic: dbscSNV1_ADA, dbscSNV1_RF. No scorers claiming Uncertain. Scorers claiming Benign: max_spliceai.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
TTN	NM_001267550.2 linkuse as main transcript	c.55432+5G>C		splice_donor_5th_base_variant, intron_variant		ENST00000589042.5
TTN-AS1	NR_038272.1 linkuse as main transcript	n.3917+986C>G		intron_variant, non_coding_transcript_variant

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
TTN	ENST00000589042.5 linkuse as main transcript	c.55432+5G>C		splice_donor_5th_base_variant, intron_variant		5	NM_001267550.2	P1
TTN-AS1	ENST00000659121.1 linkuse as main transcript	n.502+3972C>G		intron_variant, non_coding_transcript_variant

Frequencies

GnomAD3 genomes

AF:

0.0000329

AC:

AN:

152022

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.00

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.00

Gnomad ASJ

AF:

0.00

Gnomad EAS

AF:

0.000779

Gnomad SAS

AF:

0.000208

Gnomad FIN

AF:

0.00

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.00

Gnomad OTH

AF:

0.00

GnomAD3 exomes

AF:

0.0000220

AC:

AN:

226774

Hom.:

AF XY:

0.0000244

AC XY:

AN XY:

122718

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.00

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.000180

Gnomad SAS exome

AF:

0.00

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.00000944

Gnomad OTH exome

AF:

0.000186

GnomAD4 exome

AF:

0.00000974

AC:

AN:

1437810

Hom.:

Cov.:

AF XY:

0.0000154

AC XY:

AN XY:

714094

show subpopulations

Gnomad4 AFR exome

AF:

0.00

Gnomad4 AMR exome

AF:

0.00

Gnomad4 ASJ exome

AF:

0.00

Gnomad4 EAS exome

AF:

0.000101

Gnomad4 SAS exome

AF:

0.0000618

Gnomad4 FIN exome

AF:

0.00

Gnomad4 NFE exome

AF:

9.06e-7

Gnomad4 OTH exome

AF:

0.0000676

GnomAD4 genome

AF:

0.0000263

AC:

AN:

152140

Hom.:

Cov.:

AF XY:

0.0000403

AC XY:

AN XY:

74374

show subpopulations

Gnomad4 AFR

AF:

0.00

Gnomad4 AMR

AF:

0.00

Gnomad4 ASJ

AF:

0.00

Gnomad4 EAS

AF:

0.000585

Gnomad4 SAS

AF:

0.000208

Gnomad4 FIN

AF:

0.00

Gnomad4 NFE

AF:

0.00

Gnomad4 OTH

AF:

0.00

Alfa

AF:

0.0000712

Hom.:

Bravo

AF:

0.0000302

Asia WGS

AF:

0.000289

AC:

AN:

3478

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:1Uncertain:8Other:1

Revision: criteria provided, conflicting classifications

LINK: link

Submissions by phenotype

not provided

Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

GeneDx

May 12, 2014

c.50509+5 G>C: IVS236+5 G>C in intron 236 of the TTN gene (NM_001256850.1). Although the c.50509+5 G>C mutation in the TTN gene has not been reported as a disease-causing mutation or as a benign polymorphism to our knowledge, this mutation destroys the canonical splice donor site in intron 236 and is predicted to cause abnormal gene splicing. Other splice site mutations in the TTN gene have been reported in association with cardiomyopathy. Other truncating TTN variants have been reported in approximately 3% of control alleles (Herman et al., 2012). However, c.50509+5 G>C is located in the A-band region of titin, where the majority of truncating mutations associated with DCM have been reported (Herman D et al., 2012).In summary, c.50509+5 G>C in the TTN gene is interpreted as a disease-causing mutation. The variant is found in CARDIOMYOPATHY panel(s). -

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

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

Nov 01, 2023

This sequence change falls in intron 286 of the TTN gene. It does not directly change the encoded amino acid sequence of the TTN protein. It affects a nucleotide within the consensus splice site. This variant is present in population databases (rs754717390, gnomAD 0.02%). This variant has been observed in individual(s) with clinical features of dilated cardiomyopathy or left ventricular noncompaction and hypertrophic cardiomyopathy (PMID: 28822653; Invitae). ClinVar contains an entry for this variant (Variation ID: 202391). Variants that disrupt the consensus splice site are a relatively common cause of aberrant splicing (PMID: 17576681, 9536098). Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. This variant is located in the A band of TTN (PMID: 25589632). Variants in this region may be relevant for cardiac or neuromuscular disorders (PMID: 25589632, 23975875). In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. -

Early-onset myopathy with fatal cardiomyopathy

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Illumina Laboratory Services, Illumina

Jun 14, 2016

- -

Dilated Cardiomyopathy, Dominant

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Illumina Laboratory Services, Illumina

Jun 14, 2016

- -

Limb-Girdle Muscular Dystrophy, Recessive

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Illumina Laboratory Services, Illumina

Jun 14, 2016

- -

Tibial muscular dystrophy

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Illumina Laboratory Services, Illumina

Jun 14, 2016

- -

Myopathy, myofibrillar, 9, with early respiratory failure

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Illumina Laboratory Services, Illumina

Jun 14, 2016

- -

Hypertrophic cardiomyopathy

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Illumina Laboratory Services, Illumina

Jun 14, 2016

- -

Cardiovascular phenotype

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Jan 13, 2023

The c.28237+5G>C intronic variant results from a G to C substitution 5 nucleotides after coding exon 113 in the TTN gene. This variant (referred to as c.G55432+5C) co-occurred with an MYBPC3 nonsense variant in an individual from a hypertrophic cardiomyopathy cohort, and was also detected in a control individual from the same study (Zhang C et al. Can J Cardiol, 2017 Oct;33:1292-1297). This nucleotide position is highly conserved in available vertebrate species. In silico splice site analysis for this alteration is inconclusive. Since supporting evidence is limited at this time, the clinical significance of this alteration remains unclear. -

Dilated cardiomyopathy 1G;C1861065:Hypertrophic cardiomyopathy 9;C1863599:Myopathy, myofibrillar, 9, with early respiratory failure;C2673677:Early-onset myopathy with fatal cardiomyopathy

Other:1

not provided, no classification provided

phenotyping only

GenomeConnect, ClinGen

Variant interpretted as Uncertain significance and reported on 06-14-2019 by Lab or GTR ID 500188. GenomeConnect assertions are reported exactly as they appear on the patient-provided report from the testing laboratory. GenomeConnect staff make no attempt to reinterpret the clinical significance of the variant. -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

BayesDel_noAF

Benign

-0.31

Cadd

Uncertain

Dann

Benign

0.95

Splicing

Name

Calibrated prediction

Score

Prediction

dbscSNV1_ADA

Pathogenic

1.0

dbscSNV1_RF

Pathogenic

0.92

SpliceAI score (max)

0.19

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

Below is the list of publications found by LitVar. It may be empty.

Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

LitVar

Other links and lift over