2-178535442-T-C

Variant names:

• chr2-178535442-T-C
• rs878900245
• NM_001267550.2:c.101173A>G

Variant summary

Our verdict is Likely benign. The variant received -2 ACMG points: 0P and 2B. BP4_Moderate

The NM_001267550.2(TTN):​c.101173A>G​(p.Ile33725Val) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.0000192 in 1,613,846 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 14/20 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. I33725T) has been classified as Uncertain significance.

• Frequency:
  • Genomes: 𝑓 0.0000066 (0 hom., cov: 32)
  • Exomes 𝑓: 0.000021 (0 hom.)
• Consequence: TTN NM_001267550.2 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 8.02
• 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: Likely_benign. The variant received -2 ACMG points.

• BP4: Computational evidence support a benign effect (MetaRNN=0.22166127).

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.101173A>G	p.Ile33725Val	missense	Exon 358 of 363	NP_001254479.2
	TTN	NM_001256850.1		c.96250A>G	p.Ile32084Val	missense	Exon 308 of 313	NP_001243779.1
	TTN	NM_133378.4		c.93469A>G	p.Ile31157Val	missense	Exon 307 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.101173A>G	p.Ile33725Val	missense	Exon 358 of 363	ENSP00000467141.1
	TTN	ENST00000446966.2	TSL:1	c.101017A>G	p.Ile33673Val	missense	Exon 356 of 361	ENSP00000408004.2
	TTN	ENST00000436599.2	TSL:1	c.100897A>G	p.Ile33633Val	missense	Exon 356 of 361	ENSP00000405517.2

Frequencies

GnomAD3 genomes AF: 0.00000657 AC: 1 AN: 152260 Hom.: 0 Cov.: 32

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: 0.00

Gnomad NFE AF: 0.0000147

Gnomad OTH AF: 0.00

GnomAD2 exomes AF: 0.0000121 AC: 3 AN: 248878 AF XY: 0.0000148

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.0000290

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.0000177

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.0000205 AC: 30 AN: 1461586 Hom.: 0 Cov.: 38 AF XY: 0.0000206 AC XY: 15 AN XY: 727080

African (AFR) AF: 0.0000299 AC: 1 AN: 33468

American (AMR) AF: 0.0000224 AC: 1 AN: 44712

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26130

East Asian (EAS) AF: 0.00 AC: 0 AN: 39694

South Asian (SAS) AF: 0.00 AC: 0 AN: 86258

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53382

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5768

European-Non Finnish (NFE) AF: 0.0000243 AC: 27 AN: 1111802

Other (OTH) AF: 0.0000166 AC: 1 AN: 60372

GnomAD4 genome AF: 0.00000657 AC: 1 AN: 152260 Hom.: 0 Cov.: 32 AF XY: 0.00 AC XY: 0 AN XY: 74390

African (AFR) AF: 0.00 AC: 0 AN: 41472

American (AMR) AF: 0.00 AC: 0 AN: 15286

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 3472

East Asian (EAS) AF: 0.00 AC: 0 AN: 5200

South Asian (SAS) AF: 0.00 AC: 0 AN: 4836

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

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 316

European-Non Finnish (NFE) AF: 0.0000147 AC: 1 AN: 68046

Other (OTH) AF: 0.00 AC: 0 AN: 2092

Alfa AF: 0.0000659 Hom.: 0

Bravo AF: 0.0000302

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

not provided Uncertain:1

Mar 29, 2018

Athena Diagnostics

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	Benign	0.11
BayesDel_addAF	Benign	-0.20	T
BayesDel_noAF	Benign	-0.44
CADD	Benign	18
DANN	Benign	0.88
Eigen	Uncertain	0.28
Eigen_PC	Uncertain	0.43
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Benign	0.84	T
M_CAP	Benign	0.015	T
MetaRNN	Benign	0.22	T
MetaSVM	Benign	-0.87	T
MutationAssessor	Benign	1.3	L
PhyloP100		8.0
PrimateAI	Uncertain	0.51	T
PROVEAN	Benign	-0.61	N
REVEL	Benign	0.18
Sift	Benign	0.23	T
Polyphen		0.42	B
Vest4		0.20
MVP		0.49
MPC		0.12
ClinPred		0.23	T
GERP RS		5.6
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: rs878900245; hg19: chr2-179400169;