2-178548805-C-T

Variant names:

• chr2-178548805-C-T
• rs777150584
• NM_001267550.2:c.92821G>A

Variant summary

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

The ENST00000589042.5(TTN):​c.92821G>A​(p.Ala30941Thr) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000161 in 1,612,582 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 16/20 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★★). Synonymous variant affecting the same amino acid position (i.e. A30941A) has been classified as Likely benign.

• Frequency:
  • Genomes: 𝑓 0.000013 (0 hom., cov: 33)
  • Exomes 𝑓: 0.000016 (0 hom.)
• Consequence: TTN ENST00000589042.5 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:4
• Conservation: PhyloP100: 3.46
• Publications: 2 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]

ENSG00000270277 (HGNC:):

ACMG classification

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

• BP4: Computational evidence support a benign effect (MetaRNN=0.18509892).

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.92821G>A	p.Ala30941Thr	missense	Exon 339 of 363	NP_001254479.2
	TTN	NM_001256850.1		c.87898G>A	p.Ala29300Thr	missense	Exon 289 of 313	NP_001243779.1
	TTN	NM_133378.4		c.85117G>A	p.Ala28373Thr	missense	Exon 288 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.92821G>A	p.Ala30941Thr	missense	Exon 339 of 363	ENSP00000467141.1
	TTN	ENST00000446966.2	TSL:1	c.92665G>A	p.Ala30889Thr	missense	Exon 337 of 361	ENSP00000408004.2
	TTN	ENST00000436599.2	TSL:1	c.92545G>A	p.Ala30849Thr	missense	Exon 337 of 361	ENSP00000405517.2

Frequencies

GnomAD3 genomes AF: 0.0000131 AC: 2 AN: 152164 Hom.: 0 Cov.: 33

Gnomad AFR AF: 0.00

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: 0.0000294

Gnomad OTH AF: 0.00

GnomAD2 exomes AF: 0.0000161 AC: 4 AN: 247974 AF XY: 0.0000297

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.0000355

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.0000164 AC: 24 AN: 1460418 Hom.: 0 Cov.: 35 AF XY: 0.0000193 AC XY: 14 AN XY: 726556

African (AFR) AF: 0.00 AC: 0 AN: 33466

American (AMR) AF: 0.00 AC: 0 AN: 44716

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26132

East Asian (EAS) AF: 0.00 AC: 0 AN: 39686

South Asian (SAS) AF: 0.0000232 AC: 2 AN: 86258

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 52264

Middle Eastern (MID) AF: 0.000173 AC: 1 AN: 5764

European-Non Finnish (NFE) AF: 0.0000180 AC: 20 AN: 1111774

Other (OTH) AF: 0.0000166 AC: 1 AN: 60358

GnomAD4 genome AF: 0.0000131 AC: 2 AN: 152164 Hom.: 0 Cov.: 33 AF XY: 0.0000135 AC XY: 1 AN XY: 74324

African (AFR) AF: 0.00 AC: 0 AN: 41440

American (AMR) AF: 0.00 AC: 0 AN: 15266

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

East Asian (EAS) AF: 0.00 AC: 0 AN: 5190

South Asian (SAS) AF: 0.00 AC: 0 AN: 4834

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: 0.0000294 AC: 2 AN: 68030

Other (OTH) AF: 0.00 AC: 0 AN: 2094

Alfa AF: 0.0000712 Hom.: 0

Bravo AF: 0.0000189

ExAC AF: 0.0000165 AC: 2

EpiCase AF: 0.000273

EpiControl AF: 0.000119

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 (1)
-	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	-	Autosomal recessive limb-girdle muscular dystrophy type 2J;C1858763:Dilated cardiomyopathy 1G (1)
-	1	-	not provided (1)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.087
BayesDel_addAF	Benign	-0.21	T
BayesDel_noAF	Benign	-0.43
CADD	Benign	20
DANN	Benign	0.97
Eigen	Benign	0.044
Eigen_PC	Benign	0.22
FATHMM_MKL	Uncertain	0.95	D
LIST_S2	Benign	0.82	T
M_CAP	Benign	0.023	T
MetaRNN	Benign	0.19	T
MetaSVM	Benign	-0.91	T
MutationAssessor	Benign	0.91	L
PhyloP100		3.5
PrimateAI	Benign	0.45	T
PROVEAN	Benign	-2.2	N
REVEL	Benign	0.062
Sift	Benign	0.067	T
Polyphen		0.062	B
Vest4		0.33
MutPred		0.47		Gain of phosphorylation at A29300 (P = 0.055)
MVP		0.14
MPC		0.11
ClinPred		0.24	T
GERP RS		5.3
Mutation Taster		=1/99	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: rs777150584; hg19: chr2-179413532; COSMIC: COSV104641066;