rs1554011657

Variant names:

• chr2-178778887-C-A
• rs1554011657
• NM_001267550.2:c.4195G>T

Variant summary

Our verdict is Likely benign. The variant received -1 ACMG points: 2P and 3B. PM2 BP4_Moderate BP6

The NM_001267550.2(TTN):​c.4195G>T​(p.Val1399Leu) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000031 in 1,613,930 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 16/19 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars). Synonymous variant affecting the same amino acid position (i.e. V1399V) has been classified as Likely benign.

• Frequency:
  • Genomes: 𝑓 0.000013 (0 hom., cov: 33)
  • Exomes 𝑓: 0.0000021 (0 hom.)
• Consequence: TTN NM_001267550.2 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:1 B:1
• Conservation: PhyloP100: 0.307
• 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]

LOC101927055 (HGNC:):

ACMG classification

Our verdict: Likely_benign. The variant received -1 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.101762444).
• BP6: Variant 2-178778887-C-A is Benign according to our data. Variant chr2-178778887-C-A is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 467141.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_001267550.2. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	TTN	NM_001267550.2	MANE Select	c.4195G>T	p.Val1399Leu	missense	Exon 24 of 363	NP_001254479.2
	TTN	NM_001256850.1		c.4195G>T	p.Val1399Leu	missense	Exon 24 of 313	NP_001243779.1
	TTN	NM_133378.4		c.4195G>T	p.Val1399Leu	missense	Exon 24 of 312	NP_596869.4

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	TTN	ENST00000589042.5	TSL:5 MANE Select	c.4195G>T	p.Val1399Leu	missense	Exon 24 of 363	ENSP00000467141.1
	TTN	ENST00000446966.2	TSL:1	c.4195G>T	p.Val1399Leu	missense	Exon 24 of 361	ENSP00000408004.2
	TTN	ENST00000436599.2	TSL:1	c.3919G>T	p.Val1307Leu	missense	Exon 22 of 361	ENSP00000405517.2

Frequencies

GnomAD3 genomes AF: 0.0000131 AC: 2 AN: 152226 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 AF: 0.00000205 AC: 3 AN: 1461586 Hom.: 0 Cov.: 30 AF XY: 0.00000413 AC XY: 3 AN XY: 727098

African (AFR) AF: 0.00 AC: 0 AN: 33456

American (AMR) AF: 0.00 AC: 0 AN: 44716

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26132

East Asian (EAS) AF: 0.00 AC: 0 AN: 39650

South Asian (SAS) AF: 0.00 AC: 0 AN: 86254

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53390

Middle Eastern (MID) AF: 0.000347 AC: 2 AN: 5762

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 1111852

Other (OTH) AF: 0.0000166 AC: 1 AN: 60374

GnomAD4 genome AF: 0.0000131 AC: 2 AN: 152344 Hom.: 0 Cov.: 33 AF XY: 0.00 AC XY: 0 AN XY: 74494

African (AFR) AF: 0.00 AC: 0 AN: 41574

American (AMR) AF: 0.00 AC: 0 AN: 15296

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

East Asian (EAS) AF: 0.00 AC: 0 AN: 5186

South Asian (SAS) AF: 0.00 AC: 0 AN: 4832

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10628

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

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 68036

Other (OTH) AF: 0.00 AC: 0 AN: 2116

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:1 Benign:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

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

Feb 17, 2017

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

not specified Benign:1

Apr 09, 2025

Molecular Diagnostic Laboratory for Inherited Cardiovascular Disease, Montreal Heart Institute

Significance: Likely benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.11
BayesDel_addAF	Benign	-0.18	T
BayesDel_noAF	Benign	-0.50
CADD	Benign	15
DANN	Benign	0.94
Eigen	Benign	-0.46
Eigen_PC	Benign	-0.35
FATHMM_MKL	Uncertain	0.91	D
LIST_S2	Benign	0.79	T
M_CAP	Benign	0.022	T
MetaRNN	Benign	0.10	T
MetaSVM	Benign	-0.93	T
PhyloP100		0.31
PrimateAI	Benign	0.47	T
PROVEAN	Benign	-1.7	N
REVEL	Benign	0.071
Sift	Benign	0.038	D
Sift4G	Uncertain	0.021	D
Polyphen		0.0070	B
Vest4		0.086
MutPred		0.21		Loss of glycosylation at S1400 (P = 0.0936)
MVP		0.25
MPC		0.084
ClinPred		0.14	T
GERP RS		-0.84
Mutation Taster		=93/7	polymorphism

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

Other links and lift over

dbSNP: rs1554011657; hg19: chr2-179643614;