rs768786354

Variant names:

• chr2-178529960-C-A
• rs768786354
• NM_001267550.2:c.106531G>T

Your query was ambiguous. Multiple possible variants found:

• chr2-178529960-C-A
• chr2-178529960-C-G
• chr2-178529960-C-T

Variant summary

Our verdict is Pathogenic. The variant received 10 ACMG points: 10P and 0B. PM2 PM5 PP3_Strong PP5_Moderate

The NM_001267550.2(TTN):​c.106531G>T​(p.Ala35511Ser) variant causes a missense change. The variant allele was found at a frequency of 0.0000131 in 152,216 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 Likely pathogenic (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. A35511T) has been classified as Likely pathogenic.

• Frequency: Genomes: 𝑓 0.000013 (0 hom., cov: 33)
• Consequence: TTN NM_001267550.2 missense
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Likely pathogenic criteria provided, single submitter P:1
• Conservation: PhyloP100: 5.33
• Publications: 0 publications found

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

Our verdict: Pathogenic. The variant received 10 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr2-178529960-C-T is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 571263.
• PP3: Splicing predictors support a deleterious effect. Scorers claiming Pathogenic: dbscSNV1_ADA, dbscSNV1_RF, max_spliceai. No scorers claiming Uncertain. No scorers claiming Benign.
• PP5: Variant 2-178529960-C-A is Pathogenic according to our data. Variant chr2-178529960-C-A is described in ClinVar as Likely_pathogenic. ClinVar VariationId is 3762437.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
TTN	NM_001267550.2	c.106531G>T	p.Ala35511Ser	missense_variant	Exon 359 of 363	ENST00000589042.5	NP_001254479.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
TTN	ENST00000589042.5	c.106531G>T	p.Ala35511Ser	missense_variant	Exon 359 of 363	5	NM_001267550.2	ENSP00000467141.1

Frequencies

GnomAD3 genomes AF: 0.0000131 AC: 2 AN: 152098 Hom.: 0 Cov.: 33

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00633

Gnomad NFE AF: 0.00

Gnomad OTH AF: 0.00

GnomAD4 exome Cov.: 32

GnomAD4 genome AF: 0.0000131 AC: 2 AN: 152216 Hom.: 0 Cov.: 33 AF XY: 0.00 AC XY: 0 AN XY: 74424

African (AFR) AF: 0.00 AC: 0 AN: 41542

American (AMR) AF: 0.00 AC: 0 AN: 15290

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 3470

East Asian (EAS) AF: 0.00 AC: 0 AN: 5182

South Asian (SAS) AF: 0.00 AC: 0 AN: 4822

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10588

Middle Eastern (MID) AF: 0.00680 AC: 2 AN: 294

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 68004

Other (OTH) AF: 0.00 AC: 0 AN: 2112

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:1

Revision: criteria provided, single submitter

Submissions by phenotype

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

Jul 31, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces alanine, which is neutral and non-polar, with serine, which is neutral and polar, at codon 35511 of the TTN protein (p.Ala35511Ser). This variant also falls at the last nucleotide of exon 359, which is part of the consensus splice site for this exon. This variant is not present in population databases (gnomAD no frequency). This missense change has been observed in individual(s) with clinical features of limb-girdle muscular dystrophy (Invitae). It has also been observed to segregate with disease in related individuals. Experimental studies and prediction algorithms are not available or were not evaluated, and the functional significance of this variant is currently unknown. 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 M band of TTN (PMID: 25589632). Non-truncating variants in this region may be relevant for neuromuscular disorders, but have not been definitively shown to cause cardiomyopathy (PMID: 23975875). This variant disrupts the c.106531G nucleotide in the TTN gene. Other variant(s) that disrupt this nucleotide have been determined to be pathogenic (PMID: 33127292, 34440373). This suggests that this nucleotide is clinically significant, and that variants that disrupt this position are likely to be disease-causing. In summary, the currently available evidence indicates that the variant is pathogenic, but additional data are needed to prove that conclusively. Therefore, this variant has been classified as Likely Pathogenic.

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.091
BayesDel_addAF	Benign	-0.17	T
BayesDel_noAF	Benign	-0.48
CADD	Uncertain	23
DANN	Benign	0.82
DEOGEN2	Benign	0.0	.;.;.;.;.;.;.
Eigen	Benign	-0.0046
Eigen_PC	Uncertain	0.24
FATHMM_MKL	Uncertain	0.96	D
LIST_S2	Benign	0.79	T;T;T;.;T;T;T
M_CAP	Benign	0.015	T
MetaRNN	Benign	0.12	T;T;T;T;T;T;T
MetaSVM	Benign	-1.1	T
MutationAssessor	Benign	0.0	.;.;.;N;.;.;N
PhyloP100		5.3
PrimateAI	Benign	0.31	T
PROVEAN	Benign	-1.5	N;N;.;.;N;N;.
REVEL	Benign	0.020
Sift	Pathogenic	0.0	.;T;.;.;T;T;.
Sift4G	Pathogenic	0.0	.;.;.;.;.;.;.
Vest4		0.27
ClinPred		0.78	D
GERP RS		5.6
Mutation Taster		=7/93	disease causing

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	1.0
SpliceAI score (max)		0.71		Details are displayed if max score is > 0.2
DS_DL_spliceai		0.71		Position offset: 0

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

Other links and lift over

dbSNP: rs768786354; hg19: chr2-179394687;