rs769577217

Variant names:

• chr2-178562808-A-G
• rs769577217
• NM_001267550.2:c.83324T>C

Variant summary

Our verdict is Likely benign. Variant got -1 ACMG points: 0P and 1B. BP4

The NM_001267550.2(TTN):​c.83324T>C​(p.Ile27775Thr) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.0000294 in 1,461,000 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 12/19 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. I27775V) has been classified as Benign.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.000029 (0 hom.)
• Consequence: TTN NM_001267550.2 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: 9.27

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

Verdict is Likely_benign. Variant got -1 ACMG points.

• BP4: Computational evidence support a benign effect (MetaRNN=0.30883652).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
TTN	NM_001267550.2	c.83324T>C	p.Ile27775Thr	missense_variant	Exon 326 of 363	ENST00000589042.5	NP_001254479.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
TTN	ENST00000589042.5	c.83324T>C	p.Ile27775Thr	missense_variant	Exon 326 of 363	5	NM_001267550.2	ENSP00000467141.1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD3 exomes AF: 0.0000162 AC: 4 AN: 247154 Hom.: 0 AF XY: 0.0000149 AC XY: 2 AN XY: 134176

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.0000291

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad SAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.0000268

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.0000294 AC: 43 AN: 1461000 Hom.: 0 Cov.: 38 AF XY: 0.0000289 AC XY: 21 AN XY: 726774

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.0000224

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.0000378

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 33

Alfa AF: 0.0000565 Hom.: 0

Bravo AF: 0.0000227

TwinsUK AF: 0.000270 AC: 1

ALSPAC AF: 0.00 AC: 0

ExAC AF: 0.0000331 AC: 4

EpiCase AF: 0.0000545

EpiControl AF: 0.00

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

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

Oct 13, 2017

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

not provided Uncertain:1

Jul 06, 2015

Eurofins Ntd Llc (ga)

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.28
BayesDel_addAF	Benign	-0.12	T
BayesDel_noAF	Benign	-0.32
CADD	Benign	20
DANN	Benign	0.87
Eigen	Uncertain	0.31
Eigen_PC	Uncertain	0.46
FATHMM_MKL	Pathogenic	1.0	D
LIST_S2	Benign	0.82	T;T;T;.;T;T;T
M_CAP	Uncertain	0.16	D
MetaRNN	Benign	0.31	T;T;T;T;T;T;T
MetaSVM	Benign	-0.65	T
MutationAssessor	Benign	2.0	.;.;.;M;.;.;M
PrimateAI	Benign	0.41	T
PROVEAN	Uncertain	-2.5	N;D;.;.;D;D;.
REVEL	Benign	0.29
Sift	Uncertain	0.0020	D;D;.;.;D;D;.
Polyphen		0.062	.;.;.;B;.;.;B
Vest4		0.29
MutPred		0.58		.;.;.;Gain of disorder (P = 0.012);.;.;Gain of disorder (P = 0.012);
MVP		0.68
MPC		0.11
ClinPred		0.26	T
GERP RS		6.0

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: rs769577217; hg19: chr2-179427535;