chr2-178738358-C-A

Variant names:

• chr2-178738358-C-A
• rs1172448062
• NM_001267550.2:c.14095G>T

Variant summary

Our verdict is Uncertain significance. The variant received 0 ACMG points: 2P and 2B. PM2 BP4_Moderate

The NM_001267550.2(TTN):​c.14095G>T​(p.Ala4699Ser) variant causes a missense, splice region change. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a benign outcome for this variant. 13/19 in silico tools predict a benign outcome for this variant. 1/1 splice prediction tools predict no significant impact on normal splicing. Variant has been reported in ClinVar as Uncertain significance (★★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000014 (0 hom.)
  • Failed GnomAD Quality Control
• Consequence: TTN NM_001267550.2 missense, splice_region
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:3
• Conservation: PhyloP100: 5.29
• 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]

LOC124906101 (HGNC:):

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.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.22953233).

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.14095G>T	p.Ala4699Ser	missense splice_region	Exon 49 of 363	NP_001254479.2
	TTN	NM_001256850.1		c.13144G>T	p.Ala4382Ser	missense splice_region	Exon 47 of 313	NP_001243779.1
	TTN	NM_133378.4		c.10363G>T	p.Ala3455Ser	missense splice_region	Exon 46 of 312	NP_596869.4

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	TTN	ENST00000589042.5	TSL:5 MANE Select	c.14095G>T	p.Ala4699Ser	missense splice_region	Exon 49 of 363	ENSP00000467141.1
	TTN	ENST00000446966.2	TSL:1	c.14095G>T	p.Ala4699Ser	missense splice_region	Exon 49 of 361	ENSP00000408004.2
	TTN	ENST00000436599.2	TSL:1	c.13819G>T	p.Ala4607Ser	missense splice_region	Exon 47 of 361	ENSP00000405517.2

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD2 exomes AF: 0.00000814 AC: 2 AN: 245772 AF XY: 0.0000150

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.0000584

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: 0.00000137 AC: 2 AN: 1458550 Hom.: 0 Cov.: 30 AF XY: 0.00000276 AC XY: 2 AN XY: 725192

African (AFR) AF: 0.00 AC: 0 AN: 33408

American (AMR) AF: 0.0000448 AC: 2 AN: 44594

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 25994

East Asian (EAS) AF: 0.00 AC: 0 AN: 39538

South Asian (SAS) AF: 0.00 AC: 0 AN: 85848

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53250

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5744

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 1109928

Other (OTH) AF: 0.00 AC: 0 AN: 60246

GnomAD4 genome Cov.: 32

ClinVar

ClinVar submissions as Germline

Significance: Uncertain significance

Revision: criteria provided, multiple submitters, no conflicts

Pathogenic	VUS	Benign	Condition
-	1	-	Autosomal recessive limb-girdle muscular dystrophy type 2J;C1858763:Dilated cardiomyopathy 1G (1)
-	1	-	not provided (1)
-	1	-	not specified (1)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.15
BayesDel_addAF	Benign	-0.14	T
BayesDel_noAF	Benign	-0.35
CADD	Benign	23
DANN	Uncertain	0.98
Eigen	Uncertain	0.42
Eigen_PC	Uncertain	0.49
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Benign	0.73	T
M_CAP	Benign	0.079	D
MetaRNN	Benign	0.23	T
MetaSVM	Benign	-0.35	T
PhyloP100		5.3
PrimateAI	Benign	0.32	T
PROVEAN	Benign	-1.6	N
REVEL	Benign	0.20
Sift	Benign	0.70	T
Polyphen		0.65	P
Vest4		0.37
MutPred		0.42		Gain of phosphorylation at A4382 (P = 0.0227)
MVP		0.33
MPC		0.10
ClinPred		0.27	T
GERP RS		5.4
Mutation Taster		=52/48	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: rs1172448062; hg19: chr2-179603085;