NM_001267550.2:c.99277A>G

Variant names:

• chr2-178538552-T-C
• rs748796464
• NM_001267550.2:c.99277A>G

Variant summary

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

The NM_001267550.2(TTN):​c.99277A>G​(p.Thr33093Ala) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.0000048 in 1,458,374 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 13/20 in silico tools predict 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. T33093S) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0000048 (0 hom.)
• Consequence: TTN NM_001267550.2 missense
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 7.95
• 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: Likely_benign. The variant received -2 ACMG points.

• BP4: Computational evidence support a benign effect (MetaRNN=0.2622143).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
TTN	NM_001267550.2	c.99277A>G	p.Thr33093Ala	missense_variant	Exon 354 of 363	ENST00000589042.5	NP_001254479.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
TTN	ENST00000589042.5	c.99277A>G	p.Thr33093Ala	missense_variant	Exon 354 of 363	5	NM_001267550.2	ENSP00000467141.1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD2 exomes AF: 0.0000122 AC: 3 AN: 245312 AF XY: 0.00

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: 0.0000271

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000480 AC: 7 AN: 1458374 Hom.: 0 Cov.: 32 AF XY: 0.00000138 AC XY: 1 AN XY: 725278

African (AFR) AF: 0.00 AC: 0 AN: 33342

American (AMR) AF: 0.00 AC: 0 AN: 44446

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 25902

East Asian (EAS) AF: 0.00 AC: 0 AN: 39660

South Asian (SAS) AF: 0.0000117 AC: 1 AN: 85792

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53012

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5746

European-Non Finnish (NFE) AF: 0.00000540 AC: 6 AN: 1110222

Other (OTH) AF: 0.00 AC: 0 AN: 60252

GnomAD4 genome Cov.: 33

Alfa AF: 0.00 Hom.: 0

Bravo AF: 0.00000378

ExAC AF: 0.0000165 AC: 2

EpiCase AF: 0.00

EpiControl AF: 0.0000594

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.33
BayesDel_addAF	Benign	-0.076	T
BayesDel_noAF	Benign	-0.28
CADD	Benign	20
DANN	Benign	0.90
Eigen	Uncertain	0.58
Eigen_PC	Pathogenic	0.66
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Uncertain	0.86	D;D;D;.;T;D;T
M_CAP	Benign	0.035	D
MetaRNN	Benign	0.26	T;T;T;T;T;T;T
MetaSVM	Benign	-0.42	T
MutationAssessor	Benign	1.2	.;.;.;L;.;.;L
PhyloP100		8.0
PrimateAI	Uncertain	0.68	T
PROVEAN	Uncertain	-3.4	D;D;.;.;D;D;.
REVEL	Benign	0.28
Sift	Benign	0.24	T;T;.;.;T;T;.
Polyphen		1.0	.;.;.;D;.;.;D
Vest4		0.50
MutPred		0.24		.;.;.;Loss of stability (P = 0.0774);.;.;Loss of stability (P = 0.0774);
MVP		0.33
MPC		0.45
ClinPred		0.18	T
GERP RS		5.9
Mutation Taster		=57/43	polymorphism

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.010		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: rs748796464; hg19: chr2-179403279;