rs727505268

Variant names:

• chr2-178599605-C-G
• rs727505268
• NM_001267550.2:c.56296G>C

Variant summary

Our verdict is Uncertain significance. The variant received 0 ACMG points: 0P and 0B.

The NM_001267550.2(TTN):​c.56296G>C​(p.Ala18766Pro) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.0000309 in 1,454,934 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Uncertain significance (★★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.000031 (0 hom.)
• Consequence: TTN NM_001267550.2 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:3
• Conservation: PhyloP100: 7.85
• Publications: 1 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: Uncertain_significance. The variant received 0 ACMG points.

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.56296G>C	p.Ala18766Pro	missense	Exon 289 of 363	NP_001254479.2
	TTN	NM_001256850.1		c.51373G>C	p.Ala17125Pro	missense	Exon 239 of 313	NP_001243779.1
	TTN	NM_133378.4		c.48592G>C	p.Ala16198Pro	missense	Exon 238 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.56296G>C	p.Ala18766Pro	missense	Exon 289 of 363	ENSP00000467141.1
	TTN	ENST00000446966.2	TSL:1	c.56140G>C	p.Ala18714Pro	missense	Exon 287 of 361	ENSP00000408004.2
	TTN	ENST00000436599.2	TSL:1	c.56020G>C	p.Ala18674Pro	missense	Exon 287 of 361	ENSP00000405517.2

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD2 exomes AF: 0.0000532 AC: 13 AN: 244528 AF XY: 0.0000755

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.0000309 AC: 45 AN: 1454934 Hom.: 0 Cov.: 33 AF XY: 0.0000415 AC XY: 30 AN XY: 723024

African (AFR) AF: 0.00 AC: 0 AN: 33236

American (AMR) AF: 0.00 AC: 0 AN: 44232

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 25812

East Asian (EAS) AF: 0.00 AC: 0 AN: 39596

South Asian (SAS) AF: 0.000518 AC: 44 AN: 84894

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53172

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5728

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 1108164

Other (OTH) AF: 0.0000166 AC: 1 AN: 60100

GnomAD4 genome Cov.: 32

ExAC AF: 0.0000579 AC: 7

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:3

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not specified Uncertain:2

Sep 24, 2014

Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The Ala16198Pro variant in TTN has not been previously reported in individuals w ith cardiomyopathy and was absent from large population studies. Computational p rediction tools and evolutionary conservation analysis suggest that this variant may impact the protein, though this information is not predictive enough to det ermine pathogenicity. In summary, the clinical significance of the Ala16198Pro v ariant is uncertain.

Apr 10, 2015

Genetic Services Laboratory, University of Chicago

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

not provided Uncertain:1

Nov 03, 2023

Revvity Omics, Revvity

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.99
BayesDel_addAF	Benign	-0.019	T
BayesDel_noAF	Uncertain	0.060
CADD	Benign	23
DANN	Benign	0.92
Eigen	Pathogenic	1.1
Eigen_PC	Pathogenic	0.98
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.92	D
M_CAP	Benign	0.081	D
MetaRNN	Uncertain	0.67	D
MetaSVM	Pathogenic	0.85	D
MutationAssessor	Pathogenic	4.0	H
PhyloP100		7.8
PrimateAI	Uncertain	0.78	T
PROVEAN	Uncertain	-4.0	D
REVEL	Pathogenic	0.84
Sift	Uncertain	0.010	D
Polyphen		1.0	D
Vest4		0.42
MutPred		0.84		Gain of phosphorylation at T17124 (P = 0.0969)
MVP		0.77
MPC		0.53
ClinPred		0.35	T
GERP RS		5.5
Mutation Taster		=64/36	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: rs727505268; hg19: chr2-179464332;