rs376988498

Variant names:

• chr2-178572069-C-T
• rs376988498
• NM_001267550.2:c.74063G>A

Variant summary

Our verdict is Likely benign. The variant received -1 ACMG points: 0P and 1B. BP4

The NM_001267550.2(TTN):​c.74063G>A​(p.Arg24688His) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.0000279 in 1,613,076 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R24688C) has been classified as Uncertain significance.

• Frequency:
  • Genomes: 𝑓 0.000013 (0 hom., cov: 32)
  • Exomes 𝑓: 0.000029 (0 hom.)
• Consequence: TTN NM_001267550.2 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:3
• 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: Likely_benign. The variant received -1 ACMG points.

• BP4: Computational evidence support a benign effect (MetaRNN=0.33058).

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.74063G>A	p.Arg24688His	missense	Exon 326 of 363	NP_001254479.2
	TTN	NM_001256850.1		c.69140G>A	p.Arg23047His	missense	Exon 276 of 313	NP_001243779.1
	TTN	NM_133378.4		c.66359G>A	p.Arg22120His	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.74063G>A	p.Arg24688His	missense	Exon 326 of 363	ENSP00000467141.1
	TTN	ENST00000446966.2	TSL:1	c.73907G>A	p.Arg24636His	missense	Exon 324 of 361	ENSP00000408004.2
	TTN	ENST00000436599.2	TSL:1	c.73787G>A	p.Arg24596His	missense	Exon 324 of 361	ENSP00000405517.2

Frequencies

GnomAD3 genomes AF: 0.0000132 AC: 2 AN: 152014 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.0000241

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.000194

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.00

Gnomad OTH AF: 0.00

GnomAD2 exomes AF: 0.0000282 AC: 7 AN: 247808 AF XY: 0.0000149

Gnomad AFR exome AF: 0.000129

Gnomad AMR exome AF: 0.0000290

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad FIN exome AF: 0.0000465

Gnomad NFE exome AF: 0.0000268

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.0000294 AC: 43 AN: 1461062 Hom.: 0 Cov.: 38 AF XY: 0.0000261 AC XY: 19 AN XY: 726814

African (AFR) AF: 0.0000598 AC: 2 AN: 33444

American (AMR) AF: 0.0000224 AC: 1 AN: 44708

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26110

East Asian (EAS) AF: 0.000303 AC: 12 AN: 39542

South Asian (SAS) AF: 0.0000232 AC: 2 AN: 86232

European-Finnish (FIN) AF: 0.000112 AC: 6 AN: 53354

Middle Eastern (MID) AF: 0.000174 AC: 1 AN: 5758

European-Non Finnish (NFE) AF: 0.0000162 AC: 18 AN: 1111580

Other (OTH) AF: 0.0000166 AC: 1 AN: 60334

GnomAD4 genome AF: 0.0000132 AC: 2 AN: 152014 Hom.: 0 Cov.: 32 AF XY: 0.00 AC XY: 0 AN XY: 74232

African (AFR) AF: 0.0000241 AC: 1 AN: 41414

American (AMR) AF: 0.00 AC: 0 AN: 15248

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 3464

East Asian (EAS) AF: 0.000194 AC: 1 AN: 5148

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

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10618

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

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 67988

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

Alfa AF: 0.0000565 Hom.: 0

Bravo AF: 0.0000189

ESP6500AA AF: 0.00 AC: 0

ESP6500EA AF: 0.000120 AC: 1

ExAC AF: 0.0000414 AC: 5

EpiCase AF: 0.000109

EpiControl AF: 0.00

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;C1838244:Tibial muscular dystrophy;C1858763:Dilated cardiomyopathy 1G;C1861065:Hypertrophic cardiomyopathy 9;C1863599:Myopathy, myofibrillar, 9, with early respiratory failure;C2673677:Early-onset myopathy with fatal cardiomyopathy (1)
-	1	-	Cardiovascular phenotype (1)
-	1	-	not provided (1)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Uncertain	0.43
BayesDel_addAF	Benign	-0.085	T
BayesDel_noAF	Benign	-0.12
CADD	Uncertain	24
DANN	Benign	0.93
Eigen	Pathogenic	1.0
Eigen_PC	Pathogenic	1.0
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.94	D
M_CAP	Benign	0.029	D
MetaRNN	Benign	0.33	T
MetaSVM	Uncertain	0.18	D
MutationAssessor	Pathogenic	3.6	H
PhyloP100		7.9
PrimateAI	Uncertain	0.63	T
PROVEAN	Uncertain	-3.7	D
REVEL	Uncertain	0.57
Sift	Uncertain	0.0030	D
Polyphen		1.0	D
Vest4		0.34
MVP		0.58
MPC		0.52
ClinPred		0.42	T
GERP RS		6.1
Mutation Taster		=53/47	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: rs376988498; hg19: chr2-179436796;