2-178572349-C-T

Variant names:

• chr2-178572349-C-T
• rs543275318
• NM_001267550.2:c.73783G>A

Variant summary

Our verdict is Benign. The variant received -11 ACMG points: 0P and 11B. BP4_Moderate BP6 BS1 BS2

The NM_001267550.2(TTN):​c.73783G>A​(p.Ala24595Thr) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.000124 in 1,611,794 control chromosomes in the GnomAD database, including 4 homozygotes. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).

• Frequency:
  • Genomes: 𝑓 0.00014 (0 hom., cov: 32)
  • Exomes 𝑓: 0.00012 (4 hom.)
• Consequence: TTN NM_001267550.2 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:2 B:4
• Conservation: PhyloP100: 7.86
• Publications: 3 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 -11 ACMG points.

• BP4: Computational evidence support a benign effect (MetaRNN=0.13924882).
• BP6: Variant 2-178572349-C-T is Benign according to our data. Variant chr2-178572349-C-T is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 518940.
• BS1: Variant frequency is greater than expected in population sas. GnomAdExome4 allele frequency = 0.000123 (179/1459662) while in subpopulation SAS AF = 0.00188 (162/86218). AF 95% confidence interval is 0.00164. There are 4 homozygotes in GnomAdExome4. There are 126 alleles in the male GnomAdExome4 subpopulation. Median coverage is 38. This position passed quality control check.
• BS2: High Homozygotes in GnomAdExome4 at 4 AD,AR gene

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.73783G>A	p.Ala24595Thr	missense	Exon 326 of 363	NP_001254479.2
	TTN	NM_001256850.1		c.68860G>A	p.Ala22954Thr	missense	Exon 276 of 313	NP_001243779.1
	TTN	NM_133378.4		c.66079G>A	p.Ala22027Thr	missense	Exon 275 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.73783G>A	p.Ala24595Thr	missense	Exon 326 of 363	ENSP00000467141.1
	TTN	ENST00000446966.2	TSL:1	c.73627G>A	p.Ala24543Thr	missense	Exon 324 of 361	ENSP00000408004.2
	TTN	ENST00000436599.2	TSL:1	c.73507G>A	p.Ala24503Thr	missense	Exon 324 of 361	ENSP00000405517.2

Frequencies

GnomAD3 genomes AF: 0.000138 AC: 21 AN: 152132 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.0000482

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.000786

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00124

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.0000147

Gnomad OTH AF: 0.00

GnomAD2 exomes AF: 0.000258 AC: 64 AN: 248074 AF XY: 0.000327

Gnomad AFR exome AF: 0.0000646

Gnomad AMR exome AF: 0.0000290

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.0000561

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00000891

Gnomad OTH exome AF: 0.000499

GnomAD4 exome AF: 0.000123 AC: 179 AN: 1459662 Hom.: 4 Cov.: 38 AF XY: 0.000174 AC XY: 126 AN XY: 725752

African (AFR) AF: 0.0000299 AC: 1 AN: 33420

American (AMR) AF: 0.0000671 AC: 3 AN: 44684

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26104

East Asian (EAS) AF: 0.0000253 AC: 1 AN: 39536

South Asian (SAS) AF: 0.00188 AC: 162 AN: 86218

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53354

Middle Eastern (MID) AF: 0.000348 AC: 2 AN: 5752

European-Non Finnish (NFE) AF: 0.00000630 AC: 7 AN: 1110320

Other (OTH) AF: 0.0000498 AC: 3 AN: 60274

GnomAD4 genome AF: 0.000138 AC: 21 AN: 152132 Hom.: 0 Cov.: 32 AF XY: 0.000202 AC XY: 15 AN XY: 74290

African (AFR) AF: 0.0000482 AC: 2 AN: 41458

American (AMR) AF: 0.000786 AC: 12 AN: 15270

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

East Asian (EAS) AF: 0.00 AC: 0 AN: 5170

South Asian (SAS) AF: 0.00124 AC: 6 AN: 4832

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10616

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

European-Non Finnish (NFE) AF: 0.0000147 AC: 1 AN: 68000

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

Alfa AF: 0.0000868 Hom.: 0

Bravo AF: 0.000106

ExAC AF: 0.000182 AC: 22

Asia WGS AF: 0.000866 AC: 3 AN: 3478

ClinVar

ClinVar submissions as Germline

Significance: Conflicting classifications of pathogenicity

Revision: criteria provided, conflicting classifications

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

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.91
BayesDel_addAF	Benign	-0.21	T
BayesDel_noAF	Uncertain	-0.080
CADD	Benign	23
DANN	Benign	0.94
Eigen	Pathogenic	1.1
Eigen_PC	Pathogenic	1.0
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Pathogenic	0.99	D
M_CAP	Benign	0.030	D
MetaRNN	Benign	0.14	T
MetaSVM	Uncertain	0.56	D
MutationAssessor	Pathogenic	3.5	M
PhyloP100		7.9
PrimateAI	Pathogenic	0.83	D
PROVEAN	Uncertain	-2.8	D
REVEL	Uncertain	0.62
Sift	Uncertain	0.0080	D
Polyphen		1.0	D
Vest4		0.42
MutPred		0.83		Gain of phosphorylation at A22954 (P = 0.0471)
MVP		0.55
MPC		0.46
ClinPred		0.17	T
GERP RS		6.1
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.1
Mutation Taster		=84/16	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: rs543275318; hg19: chr2-179437076; COSMIC: COSV60321839; COSMIC: COSV60321839;