chr2-178722367-C-T

Variant names:

• chr2-178722367-C-T
• rs759713604
• NM_001267550.2:c.22420G>A

Variant summary

Our verdict is Likely benign. The variant received -3 ACMG points: 0P and 3B. BP4_Moderate BP6

The NM_001267550.2(TTN):​c.22420G>A​(p.Ala7474Thr) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.000269 in 1,613,156 control chromosomes in the GnomAD database, including 1 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 0.000072 (0 hom., cov: 33)
  • Exomes 𝑓: 0.00029 (1 hom.)
• Consequence: TTN NM_001267550.2 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:7 B:4
• Conservation: PhyloP100: 7.90
• Publications: 4 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 -3 ACMG points.

• BP4: Computational evidence support a benign effect (MetaRNN=0.23512217).
• BP6: Variant 2-178722367-C-T is Benign according to our data. Variant chr2-178722367-C-T is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 203313.

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.22420G>A	p.Ala7474Thr	missense	Exon 77 of 363	NP_001254479.2	Q8WZ42-12
	TTN	NM_001256850.1		c.21469G>A	p.Ala7157Thr	missense	Exon 75 of 313	NP_001243779.1	Q8WZ42-1
	TTN	NM_133378.4		c.18688G>A	p.Ala6230Thr	missense	Exon 74 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.22420G>A	p.Ala7474Thr	missense	Exon 77 of 363	ENSP00000467141.1	Q8WZ42-12
	TTN	ENST00000446966.2	TSL:1	c.22420G>A	p.Ala7474Thr	missense	Exon 77 of 361	ENSP00000408004.2	A0A1B0GXE3
	TTN	ENST00000436599.2	TSL:1	c.22144G>A	p.Ala7382Thr	missense	Exon 75 of 361	ENSP00000405517.2	A0A0C4DG59

Frequencies

GnomAD3 genomes AF: 0.0000724 AC: 11 AN: 152030 Hom.: 0 Cov.: 33

Gnomad AFR AF: 0.0000241

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.0000657

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: 0.000132

Gnomad OTH AF: 0.00

GnomAD2 exomes AF: 0.000121 AC: 30 AN: 247460 AF XY: 0.000119

Gnomad AFR exome AF: 0.0000648

Gnomad AMR exome AF: 0.0000291

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.000143

Gnomad OTH exome AF: 0.000501

GnomAD4 exome AF: 0.000290 AC: 423 AN: 1461126 Hom.: 1 Cov.: 32 AF XY: 0.000282 AC XY: 205 AN XY: 726830

African (AFR) AF: 0.0000598 AC: 2 AN: 33442

American (AMR) AF: 0.0000448 AC: 2 AN: 44686

Ashkenazi Jewish (ASJ) AF: 0.0000383 AC: 1 AN: 26120

East Asian (EAS) AF: 0.00 AC: 0 AN: 39666

South Asian (SAS) AF: 0.000220 AC: 19 AN: 86222

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53342

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5762

European-Non Finnish (NFE) AF: 0.000352 AC: 391 AN: 1111554

Other (OTH) AF: 0.000133 AC: 8 AN: 60332

GnomAD4 genome AF: 0.0000724 AC: 11 AN: 152030 Hom.: 0 Cov.: 33 AF XY: 0.0000404 AC XY: 3 AN XY: 74240

African (AFR) AF: 0.0000241 AC: 1 AN: 41408

American (AMR) AF: 0.0000657 AC: 1 AN: 15226

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

East Asian (EAS) AF: 0.00 AC: 0 AN: 5184

South Asian (SAS) AF: 0.00 AC: 0 AN: 4830

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10592

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

European-Non Finnish (NFE) AF: 0.000132 AC: 9 AN: 68006

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

Alfa AF: 0.000203 Hom.: 0

Bravo AF: 0.0000831

ExAC AF: 0.000124 AC: 15

EpiCase AF: 0.0000546

EpiControl AF: 0.000237

ClinVar

ClinVar submissions

Significance: Conflicting classifications of pathogenicity

Revision: criteria provided, conflicting classifications

Pathogenic	VUS	Benign	Condition
-	1	1	not specified (2)
-	1	-	Autosomal recessive limb-girdle muscular dystrophy type 2J (1)
-	1	-	Autosomal recessive limb-girdle muscular dystrophy type 2J;C1858763:Dilated cardiomyopathy 1G (1)
-	1	-	Cardiomyopathy (1)
-	-	1	Congenital myopathy (1)
-	1	-	Dilated cardiomyopathy 1G (1)
-	1	-	Early-onset myopathy with fatal cardiomyopathy (1)
-	-	1	Myopathy, myofibrillar, 9, with early respiratory failure (1)
-	1	-	not provided (1)
-	-	1	Tibial muscular dystrophy (1)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Uncertain	0.51
BayesDel_addAF	Benign	-0.18	T
BayesDel_noAF	Benign	-0.20
CADD	Benign	23
DANN	Benign	0.95
Eigen	Pathogenic	0.90
Eigen_PC	Pathogenic	0.91
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Benign	0.84	T
M_CAP	Benign	0.017	T
MetaRNN	Benign	0.24	T
MetaSVM	Uncertain	-0.074	T
PhyloP100		7.9
PrimateAI	Uncertain	0.64	T
PROVEAN	Benign	-2.3	N
REVEL	Uncertain	0.46
Sift	Benign	0.40	T
Polyphen		1.0	D
Vest4		0.24
MVP		0.45
MPC		0.46
ClinPred		0.099	T
GERP RS		6.2
Mutation Taster		=35/65	disease causing

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: rs759713604; hg19: chr2-179587094;