rs794729484

Variant names:

• chr2-178577635-T-G
• rs794729484
• NM_001267550.2:c.68791A>C

Variant summary

Our verdict is Likely benign. The variant received -2 ACMG points: 0P and 2B. BP4_Moderate

The NM_001267550.2(TTN):​c.68791A>C​(p.Ser22931Arg) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000558 in 1,612,034 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 14/20 in silico tools predict 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. S22931N) has been classified as Likely benign.

• Frequency:
  • Genomes: 𝑓 0.000033 (0 hom., cov: 32)
  • Exomes 𝑓: 0.0000027 (0 hom.)
• Consequence: TTN NM_001267550.2 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: 0.182
• 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]

ENSG00000271011 (HGNC:):

ACMG classification

Our verdict: Likely_benign. The variant received -2 ACMG points.

• BP4: Computational evidence support a benign effect (MetaRNN=0.15327862).

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.68791A>C	p.Ser22931Arg	missense	Exon 323 of 363	NP_001254479.2
	TTN	NM_001256850.1		c.63868A>C	p.Ser21290Arg	missense	Exon 273 of 313	NP_001243779.1
	TTN	NM_133378.4		c.61087A>C	p.Ser20363Arg	missense	Exon 272 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.68791A>C	p.Ser22931Arg	missense	Exon 323 of 363	ENSP00000467141.1
	TTN	ENST00000446966.2	TSL:1	c.68635A>C	p.Ser22879Arg	missense	Exon 321 of 361	ENSP00000408004.2
	TTN	ENST00000436599.2	TSL:1	c.68515A>C	p.Ser22839Arg	missense	Exon 321 of 361	ENSP00000405517.2

Frequencies

GnomAD3 genomes AF: 0.0000329 AC: 5 AN: 152140 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.000121

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: 0.00

Gnomad OTH AF: 0.00

GnomAD4 exome AF: 0.00000274 AC: 4 AN: 1459894 Hom.: 0 Cov.: 35 AF XY: 0.00000413 AC XY: 3 AN XY: 726090

African (AFR) AF: 0.0000898 AC: 3 AN: 33406

American (AMR) AF: 0.00 AC: 0 AN: 44580

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26086

East Asian (EAS) AF: 0.00 AC: 0 AN: 39542

South Asian (SAS) AF: 0.00 AC: 0 AN: 85830

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53258

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5756

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 1111144

Other (OTH) AF: 0.0000166 AC: 1 AN: 60292

GnomAD4 genome AF: 0.0000329 AC: 5 AN: 152140 Hom.: 0 Cov.: 32 AF XY: 0.0000135 AC XY: 1 AN XY: 74310

African (AFR) AF: 0.000121 AC: 5 AN: 41458

American (AMR) AF: 0.00 AC: 0 AN: 15268

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 3472

East Asian (EAS) AF: 0.00 AC: 0 AN: 5166

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

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10628

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

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 67998

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

Alfa AF: 0.00 Hom.: 0

Bravo AF: 0.0000227

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	-	not specified (1)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Uncertain	0.52
BayesDel_addAF	Benign	-0.021	T
BayesDel_noAF	Benign	-0.27
CADD	Benign	19
DANN	Benign	0.82
Eigen	Benign	0.16
Eigen_PC	Benign	0.10
FATHMM_MKL	Benign	0.28	N
LIST_S2	Uncertain	0.91	D
M_CAP	Benign	0.049	D
MetaRNN	Benign	0.15	T
MetaSVM	Benign	-0.53	T
MutationAssessor	Benign	2.0	M
PhyloP100		0.18
PrimateAI	Uncertain	0.71	T
PROVEAN	Uncertain	-3.1	D
REVEL	Benign	0.28
Sift	Uncertain	0.0070	D
Polyphen		0.88	P
Vest4		0.41
MutPred		0.26		Loss of phosphorylation at S21290 (P = 0.0436)
MVP		0.25
MPC		0.18
ClinPred		0.35	T
GERP RS		4.6
Mutation Taster		=69/31	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: rs794729484; hg19: chr2-179442362;