2-178613926-G-T

Variant names:

• chr2-178613926-G-T
• rs200121902
• NM_001267550.2:c.49357C>A

Variant summary

Our verdict is Benign. The variant received -9 ACMG points: 0P and 9B. BP4_Strong BP6 BS1

The ENST00000589042.5(TTN):​c.49357C>A​(p.Pro16453Thr) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000964 in 1,607,776 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 12/20 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. P16453L) has been classified as Uncertain significance.

• Frequency:
  • Genomes: 𝑓 0.00054 (0 hom., cov: 32)
  • Exomes 𝑓: 0.000050 (0 hom.)
• Consequence: TTN ENST00000589042.5 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:2 B:5
• Conservation: PhyloP100: 3.56
• 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: Benign. The variant received -9 ACMG points.

• BP4: Computational evidence support a benign effect (MetaRNN=0.035306633).
• BP6: Variant 2-178613926-G-T is Benign according to our data. Variant chr2-178613926-G-T is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 413133.
• BS1: Variant frequency is greater than expected in population afr. GnomAdExome4 allele frequency = 0.0000501 (73/1455734) while in subpopulation AFR AF = 0.00202 (67/33128). AF 95% confidence interval is 0.00163. There are 0 homozygotes in GnomAdExome4. There are 35 alleles in the male GnomAdExome4 subpopulation. Median coverage is 32. This position passed quality control check.

Variant Effect in Transcripts

ACMG analysis was done for transcript: ENST00000589042.5. 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.49357C>A	p.Pro16453Thr	missense	Exon 263 of 363	NP_001254479.2
	TTN	NM_001256850.1		c.44434C>A	p.Pro14812Thr	missense	Exon 213 of 313	NP_001243779.1
	TTN	NM_133378.4		c.41653C>A	p.Pro13885Thr	missense	Exon 212 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.49357C>A	p.Pro16453Thr	missense	Exon 263 of 363	ENSP00000467141.1
	TTN	ENST00000446966.2	TSL:1	c.49201C>A	p.Pro16401Thr	missense	Exon 261 of 361	ENSP00000408004.2
	TTN	ENST00000436599.2	TSL:1	c.49081C>A	p.Pro16361Thr	missense	Exon 261 of 361	ENSP00000405517.2

Frequencies

GnomAD3 genomes AF: 0.000540 AC: 82 AN: 151924 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.00193

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: 0.000478

GnomAD2 exomes AF: 0.000127 AC: 31 AN: 244278 AF XY: 0.000106

Gnomad AFR exome AF: 0.00189

Gnomad AMR exome AF: 0.0000297

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00000900

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.0000501 AC: 73 AN: 1455734 Hom.: 0 Cov.: 32 AF XY: 0.0000484 AC XY: 35 AN XY: 723676

African (AFR) AF: 0.00202 AC: 67 AN: 33128

American (AMR) AF: 0.0000228 AC: 1 AN: 43940

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 25902

East Asian (EAS) AF: 0.00 AC: 0 AN: 39552

South Asian (SAS) AF: 0.00 AC: 0 AN: 85262

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53266

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5716

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 1108892

Other (OTH) AF: 0.0000832 AC: 5 AN: 60076

GnomAD4 genome AF: 0.000539 AC: 82 AN: 152042 Hom.: 0 Cov.: 32 AF XY: 0.000565 AC XY: 42 AN XY: 74304

African (AFR) AF: 0.00193 AC: 80 AN: 41536

American (AMR) AF: 0.00 AC: 0 AN: 15254

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 3466

East Asian (EAS) AF: 0.00 AC: 0 AN: 5118

South Asian (SAS) AF: 0.00 AC: 0 AN: 4814

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10610

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 294

European-Non Finnish (NFE) AF: 0.0000147 AC: 1 AN: 67926

Other (OTH) AF: 0.000473 AC: 1 AN: 2112

Alfa AF: 0.000213 Hom.: 0

Bravo AF: 0.000604

ESP6500AA AF: 0.00207 AC: 8

ESP6500EA AF: 0.00 AC: 0

ExAC AF: 0.000157 AC: 19

ClinVar

ClinVar submissions as Germline

Significance: Conflicting classifications of pathogenicity

Revision: criteria provided, conflicting classifications

Pathogenic	VUS	Benign	Condition
-	2	1	not provided (3)
-	-	1	Autosomal recessive limb-girdle muscular dystrophy type 2J;C1858763:Dilated cardiomyopathy 1G (1)
-	-	1	Cardiovascular phenotype (1)
-	-	1	not specified (1)
-	-	1	TTN-related disorder (1)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.29
BayesDel_addAF	Benign	-0.34	T
BayesDel_noAF	Benign	-0.26
CADD	Benign	21
DANN	Benign	0.87
Eigen	Pathogenic	0.88
Eigen_PC	Pathogenic	0.85
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Uncertain	0.90	D
M_CAP	Benign	0.025	D
MetaRNN	Benign	0.035	T
MetaSVM	Uncertain	0.056	D
MutationAssessor	Pathogenic	3.2	M
PhyloP100		3.6
PrimateAI	Benign	0.48	T
PROVEAN	Pathogenic	-5.1	D
REVEL	Uncertain	0.42
Sift	Benign	0.036	D
Polyphen		0.99	D
Vest4		0.40
MVP		0.41
MPC		0.42
ClinPred		0.17	T
GERP RS		6.1
Mutation Taster		=79/21	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: rs200121902; hg19: chr2-179478653; COSMIC: COSV104642027;