2-178526969-G-A

Position:

• chr2-178526969-G-A

Variant summary

Our verdict is Benign. Variant got -14 ACMG points: 0P and 14B. BP4_Strong BP6_Moderate BS1 BS2

The NM_001267550.2(TTN):​c.*43C>T variant causes a 3 prime UTR change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000975 in 1,484,682 control chromosomes in the GnomAD database, including 19 homozygotes. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Likely benign (★).

• Frequency:
  • Genomes: 𝑓 0.0053 (8 hom., cov: 33)
  • Exomes 𝑓: 0.00048 (11 hom.)
• Consequence: TTN NM_001267550.2 3_prime_UTR
• Clinical Significance: Likely benign criteria provided, single submitter B:1
• Conservation: PhyloP100: 1.40

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 -14 ACMG points.

• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.57).
• BP6: Variant 2-178526969-G-A is Benign according to our data. Variant chr2-178526969-G-A is described in ClinVar as [Likely_benign]. Clinvar id is 1214912.Status of the report is criteria_provided_single_submitter, 1 stars.
• BS1: Variant frequency is greater than expected in population afr. gnomad4 allele frequency = 0.00528 (804/152274) while in subpopulation AFR AF= 0.0182 (758/41552). AF 95% confidence interval is 0.0172. There are 8 homozygotes in gnomad4. There are 386 alleles in male gnomad4 subpopulation. Median coverage is 33. This position pass quality control queck.
• BS2: High Homozygotes in GnomAd4 at 8 AD,AR gene

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
TTN	NM_001267550.2	c.*43C>T		3_prime_UTR_variant	363/363	ENST00000589042.5
TTN-AS1	NR_038272.1	n.219+3333G>A		intron_variant, non_coding_transcript_variant

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
TTN	ENST00000589042.5	c.*43C>T		3_prime_UTR_variant	363/363	5	NM_001267550.2	P1
TTN-AS1	ENST00000659121.1	n.416+3333G>A		intron_variant, non_coding_transcript_variant

Frequencies

GnomAD3 genomes AF: 0.00528 AC: 804 AN: 152156 Hom.: 8 Cov.: 33

Gnomad AFR AF: 0.0183

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00216

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.000414

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.0000882

Gnomad OTH AF: 0.00239

GnomAD3 exomes AF: 0.00158 AC: 285 AN: 179848 Hom.: 3 AF XY: 0.00122 AC XY: 118 AN XY: 96734

Gnomad AFR exome AF: 0.0195

Gnomad AMR exome AF: 0.000671

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad SAS exome AF: 0.000388

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.0000464

Gnomad OTH exome AF: 0.000718

GnomAD4 exome AF: 0.000483 AC: 643 AN: 1332408 Hom.: 11 Cov.: 26 AF XY: 0.000423 AC XY: 276 AN XY: 651856

Gnomad4 AFR exome AF: 0.0170

Gnomad4 AMR exome AF: 0.000914

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.000224

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.0000441

Gnomad4 OTH exome AF: 0.000730

GnomAD4 genome AF: 0.00528 AC: 804 AN: 152274 Hom.: 8 Cov.: 33 AF XY: 0.00518 AC XY: 386 AN XY: 74454

Gnomad4 AFR AF: 0.0182

Gnomad4 AMR AF: 0.00216

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.000414

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.0000882

Gnomad4 OTH AF: 0.00236

Alfa AF: 0.00270 Hom.: 2

Bravo AF: 0.00554

Asia WGS AF: 0.000577 AC: 2 AN: 3478

ClinVar

Significance: Likely benign

Submissions summary: Benign:1

Revision: criteria provided, single submitter

Submissions by phenotype

not provided Benign:1

Likely benign, criteria provided, single submitter

clinical testing

GeneDx

Jul 14, 2018

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.57
CADD	Benign	3.6
DANN	Benign	0.72

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: rs72629794; hg19: chr2-179391696; COSMIC: COSV100587900; COSMIC: COSV100587900;