2-178609278-A-T

Variant names:

• chr2-178609278-A-T
• rs374254751
• NM_001267550.2:c.52032T>A

Variant summary

Our verdict is Uncertain significance. The variant received 3 ACMG points: 3P and 0B. PM2 PP3

The NM_001267550.2(TTN):​c.52032T>A​(p.His17344Gln) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000000698 in 1,431,646 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar. Another variant affecting the same amino acid position, but resulting in a different missense (i.e. H17344R) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 7.0e-7 (0 hom.)
• Consequence: TTN NM_001267550.2 missense
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 0.237
• 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]

ACMG classification

Our verdict: Uncertain_significance. The variant received 3 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: Splicing predictors support a deleterious effect. Scorers claiming Pathogenic: max_spliceai. No scorers claiming Uncertain. No scorers claiming Benign.

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.52032T>A	p.His17344Gln	missense	Exon 273 of 363	NP_001254479.2	Q8WZ42-12
	TTN	NM_001256850.1		c.47109T>A	p.His15703Gln	missense	Exon 223 of 313	NP_001243779.1	Q8WZ42-1
	TTN	NM_133378.4		c.44328T>A	p.His14776Gln	missense	Exon 222 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.52032T>A	p.His17344Gln	missense	Exon 273 of 363	ENSP00000467141.1	Q8WZ42-12
	TTN	ENST00000446966.2	TSL:1	c.51876T>A	p.His17292Gln	missense	Exon 271 of 361	ENSP00000408004.2	A0A1B0GXE3
	TTN	ENST00000436599.2	TSL:1	c.51756T>A	p.His17252Gln	missense	Exon 271 of 361	ENSP00000405517.2	A0A0C4DG59

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome AF: 6.98e-7 AC: 1 AN: 1431646 Hom.: 0 Cov.: 32 AF XY: 0.00 AC XY: 0 AN XY: 709542

African (AFR) AF: 0.00 AC: 0 AN: 32426

American (AMR) AF: 0.00 AC: 0 AN: 41516

Ashkenazi Jewish (ASJ) AF: 0.0000419 AC: 1 AN: 23890

East Asian (EAS) AF: 0.00 AC: 0 AN: 39272

South Asian (SAS) AF: 0.00 AC: 0 AN: 79690

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 52046

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5600

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 1098168

Other (OTH) AF: 0.00 AC: 0 AN: 59038

GnomAD4 genome Cov.: 33

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.32
BayesDel_addAF	Benign	-0.048	T
BayesDel_noAF	Benign	-0.31
CADD	Benign	20
DANN	Benign	0.85
Eigen	Uncertain	0.21
Eigen_PC	Benign	0.15
FATHMM_MKL	Uncertain	0.85	D
LIST_S2	Benign	0.82	T
M_CAP	Benign	0.028	D
MetaRNN	Benign	0.29	T
MetaSVM	Benign	-0.53	T
MutationAssessor	Uncertain	2.1	M
PhyloP100		0.24
PrimateAI	Uncertain	0.66	T
PROVEAN	Pathogenic	-5.4	D
REVEL	Benign	0.28
Sift	Benign	0.11	T
Polyphen		0.99	D
Vest4		0.41
MutPred		0.39		Loss of catalytic residue at D15702 (P = 0.0562)
MVP		0.37
MPC		0.39
ClinPred		0.37	T
GERP RS		1.9
Mutation Taster		=86/14	polymorphism

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.74		Details are displayed if max score is > 0.2
DS_DG_spliceai		0.74		Position offset: -1

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Other links and lift over

dbSNP: rs374254751; hg19: chr2-179474005;