rs16866490

Positions:

• chr2-178749332-T-C

Variant summary

Our verdict is Benign. Variant got -21 ACMG points: 0P and 21B. BP4_Strong BP6_Very_Strong BP7 BS1 BS2

The NM_133379.5(TTN):​c.13068A>G​(p.Gln4356=) variant causes a synonymous change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00112 in 1,612,694 control chromosomes in the GnomAD database, including 18 homozygotes. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Benign (★★).

• Frequency:
  • Genomes: 𝑓 0.0058 (6 hom., cov: 32)
  • Exomes 𝑓: 0.00064 (12 hom.)
• Consequence: TTN NM_133379.5 synonymous
• Clinical Significance: Benign criteria provided, multiple submitters, no conflicts B:5
• Conservation: PhyloP100: -1.17

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

Verdict is Benign. Variant got -21 ACMG points.

• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.86).
• BP6: Variant 2-178749332-T-C is Benign according to our data. Variant chr2-178749332-T-C is described in ClinVar as [Benign]. Clinvar id is 177966.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr2-178749332-T-C is described in Lovd as [Benign].
• BP7: Synonymous conserved (PhyloP=-1.17 with no splicing effect.
• BS1: Variant frequency is greater than expected in population afr. gnomad4 allele frequency = 0.00578 (879/152076) while in subpopulation AFR AF= 0.0202 (839/41522). AF 95% confidence interval is 0.0191. There are 6 homozygotes in gnomad4. There are 401 alleles in male gnomad4 subpopulation. Median coverage is 32. This position pass quality control queck.
• BS2: High Homozygotes in GnomAd4 at 6 AD,AR gene

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
TTN	NM_133379.5	c.13068A>G	p.Gln4356=	synonymous_variant	46/46	ENST00000360870.10
TTN	NM_001267550.2	c.11311+3792A>G		intron_variant		ENST00000589042.5

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
TTN	ENST00000360870.10	c.13068A>G	p.Gln4356=	synonymous_variant	46/46	5	NM_133379.5
TTN	ENST00000589042.5	c.11311+3792A>G		intron_variant		5	NM_001267550.2	P1
TTN-AS1	ENST00000659121.1	n.1223+6362T>C		intron_variant, non_coding_transcript_variant

Frequencies

GnomAD3 genomes AF: 0.00576 AC: 875 AN: 151958 Hom.: 6 Cov.: 32

Gnomad AFR AF: 0.0202

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.000985

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.000207

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00316

Gnomad NFE AF: 0.000103

Gnomad OTH AF: 0.00766

GnomAD3 exomes AF: 0.00147 AC: 366 AN: 249766 Hom.: 4 AF XY: 0.00109 AC XY: 147 AN XY: 135092

Gnomad AFR exome AF: 0.0202

Gnomad AMR exome AF: 0.000840

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad SAS exome AF: 0.0000327

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.0000709

Gnomad OTH exome AF: 0.000658

GnomAD4 exome AF: 0.000640 AC: 935 AN: 1460618 Hom.: 12 Cov.: 36 AF XY: 0.000561 AC XY: 408 AN XY: 726636

Gnomad4 AFR exome AF: 0.0230

Gnomad4 AMR exome AF: 0.000962

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.0000812

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.0000216

Gnomad4 OTH exome AF: 0.00143

GnomAD4 genome AF: 0.00578 AC: 879 AN: 152076 Hom.: 6 Cov.: 32 AF XY: 0.00539 AC XY: 401 AN XY: 74352

Gnomad4 AFR AF: 0.0202

Gnomad4 AMR AF: 0.000984

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.000207

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.000103

Gnomad4 OTH AF: 0.00758

Alfa AF: 0.00237 Hom.: 1

Bravo AF: 0.00668

Asia WGS AF: 0.000578 AC: 2 AN: 3476

EpiCase AF: 0.0000546

EpiControl AF: 0.000119

ClinVar

Significance: Benign

Submissions summary: Benign:5

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not specified Benign:4

Benign, criteria provided, single submitter	clinical testing	GeneDx	Dec 19, 2014	This variant is considered likely benign or benign based on one or more of the following criteria: it is a conservative change, it occurs at a poorly conserved position in the protein, it is predicted to be benign by multiple in silico algorithms, and/or has population frequency not consistent with disease. -
Benign, criteria provided, single submitter	clinical testing	Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine	Mar 19, 2013	Gln4356Gln in exon 45A of TTN: This variant is not expected to have clinical sig nificance because it has been identified in 1.8% (78/4406) of African American c hromosomes from a broad population by the NHLBI Exome Sequencing Project (http:/ /evs.gs.washington.edu/EVS/; dbSNP rs16866490). -
Benign, no assertion criteria provided	clinical testing	Clinical Genetics DNA and cytogenetics Diagnostics Lab, Erasmus MC, Erasmus Medical Center	-	- -
Benign, no assertion criteria provided	clinical testing	Clinical Genetics, Academic Medical Center	-	- -

not provided Benign:1

Benign, criteria provided, single submitter

clinical testing

ARUP Laboratories, Molecular Genetics and Genomics, ARUP Laboratories

Feb 04, 2021

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.86
CADD	Benign	0.095
DANN	Benign	0.54

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

Publications

LitVar

Other links and lift over

dbSNP: rs16866490; hg19: chr2-179614059;