2-178593853-G-T

Variant names:

• chr2-178593853-G-T
• rs367624056
• NM_001267550.2:c.58447C>A

Variant summary

Our verdict is Uncertain significance. The variant received 2 ACMG points: 2P and 0B. PM2

The NM_001267550.2(TTN):​c.58447C>A​(p.Pro19483Thr) variant causes a missense change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar. Another variant affecting the same amino acid position, but resulting in a different missense (i.e. P19483A) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
  • Failed GnomAD Quality Control
• Consequence: TTN NM_001267550.2 missense
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 9.93
• 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 2 ACMG points.

• PM2: Very rare variant in population databases, with high coverage

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

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	TTN	NM_001267550.2	MANE Select	c.58447C>A	p.Pro19483Thr	missense	Exon 298 of 363	NP_001254479.2	Q8WZ42-12
	TTN	NM_001256850.1		c.53524C>A	p.Pro17842Thr	missense	Exon 248 of 313	NP_001243779.1	Q8WZ42-1
	TTN	NM_133378.4		c.50743C>A	p.Pro16915Thr	missense	Exon 247 of 312	NP_596869.4	Q8WZ42-11

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	TTN	ENST00000589042.5	TSL:5 MANE Select	c.58447C>A	p.Pro19483Thr	missense	Exon 298 of 363	ENSP00000467141.1	Q8WZ42-12
	TTN	ENST00000446966.2	TSL:1	c.58291C>A	p.Pro19431Thr	missense	Exon 296 of 361	ENSP00000408004.2	A0A1B0GXE3
	TTN	ENST00000436599.2	TSL:1	c.58171C>A	p.Pro19391Thr	missense	Exon 296 of 361	ENSP00000405517.2	A0A0C4DG59

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD2 exomes AF: 0.00000405 AC: 1 AN: 246664 AF XY: 0.00000747

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.0000292

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 Data not reliable, filtered out with message: AS_VQSR AF: 6.85e-7 AC: 1 AN: 1460518 Hom.: 0 Cov.: 35 AF XY: 0.00000138 AC XY: 1 AN XY: 726472

⚠️ The allele balance in gnomAD version 4 Exomes is significantly skewed from the expected value of 0.5.

African (AFR) AF: 0.00 AC: 0 AN: 33430

American (AMR) AF: 0.0000224 AC: 1 AN: 44598

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26114

East Asian (EAS) AF: 0.00 AC: 0 AN: 39450

South Asian (SAS) AF: 0.00 AC: 0 AN: 86046

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53304

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5756

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 1111516

Other (OTH) AF: 0.00 AC: 0 AN: 60304

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0), which strongly suggests a high chance of mosaicism in these individuals.

GnomAD4 genome Cov.: 32

ExAC AF: 0.00000828 AC: 1

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.82
BayesDel_addAF	Benign	-0.021	T
BayesDel_noAF	Benign	-0.18
CADD	Benign	22
DANN	Benign	0.88
Eigen	Pathogenic	1.2
Eigen_PC	Pathogenic	1.1
FATHMM_MKL	Pathogenic	1.0	D
LIST_S2	Uncertain	0.94	D
M_CAP	Benign	0.0099	T
MetaRNN	Uncertain	0.44	T
MetaSVM	Uncertain	0.39	D
MutationAssessor	Pathogenic	3.9	H
PhyloP100		9.9
PrimateAI	Uncertain	0.60	T
PROVEAN	Pathogenic	-6.3	D
REVEL	Uncertain	0.55
Sift	Uncertain	0.0030	D
Polyphen		1.0	D
Vest4		0.35
MutPred		0.72		Gain of glycosylation at P17842 (P = 0.0062)
MVP		0.57
MPC		0.49
ClinPred		0.37	T
GERP RS		5.9
Mutation Taster		=59/41	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: rs367624056; hg19: chr2-179458580;