2-178766630-TAAA-T

Variant names:

• chr2-178766630-TAAA-T
• rs201990196
• NM_001267550.2:c.9472-21_9472-19delTTT

Variant summary

Our verdict is Likely benign. The variant received -2 ACMG points: 0P and 2B. BP6_Moderate

The NM_001267550.2(TTN):​c.9472-21_9472-19delTTT variant causes a intron change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000902 in 1,441,776 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Likely benign (★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000090 (0 hom.)
• Consequence: TTN NM_001267550.2 intron
• Clinical Significance: Likely benign criteria provided, single submitter B:1
• Conservation: PhyloP100: 1.53
• Publications: 1 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.

• BP6: Variant 2-178766630-TAAA-T is Benign according to our data. Variant chr2-178766630-TAAA-T is described in ClinVar as Likely_benign. ClinVar VariationId is 1653891.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
TTN	NM_001267550.2	c.9472-21_9472-19delTTT		intron_variant	Intron 40 of 362	ENST00000589042.5	NP_001254479.2
TTN	NM_133379.5	c.9472-21_9472-19delTTT		intron_variant	Intron 40 of 45	ENST00000360870.10	NP_596870.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
TTN	ENST00000589042.5	c.9472-21_9472-19delTTT		intron_variant	Intron 40 of 362	5	NM_001267550.2	ENSP00000467141.1
TTN	ENST00000360870.10	c.9472-21_9472-19delTTT		intron_variant	Intron 40 of 45	5	NM_133379.5	ENSP00000354117.4

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD2 exomes AF: 0.00000409 AC: 1 AN: 244338 AF XY: 0.00000756

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: 0.00

Gnomad OTH exome AF: 0.000167

GnomAD4 exome AF: 0.00000902 AC: 13 AN: 1441776 Hom.: 0 AF XY: 0.0000125 AC XY: 9 AN XY: 718468

⚠️ The allele balance in gnomAD version 4 Exomes is significantly skewed from the expected value of 0.5.

African (AFR) AF: 0.00 AC: 0 AN: 33038

American (AMR) AF: 0.00 AC: 0 AN: 44502

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 25982

East Asian (EAS) AF: 0.00 AC: 0 AN: 39410

South Asian (SAS) AF: 0.0000117 AC: 1 AN: 85776

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 52930

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5568

European-Non Finnish (NFE) AF: 0.0000100 AC: 11 AN: 1094862

Other (OTH) AF: 0.0000167 AC: 1 AN: 59708

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0.000000), which strongly suggests a high chance of mosaicism in these individuals.

GnomAD4 genome Cov.: 32

Alfa AF: 0.00 Hom.: 0

ClinVar

Significance: Likely benign

Submissions summary: Benign:1

Revision: criteria provided, single submitter

Submissions by phenotype

Autosomal recessive limb-girdle muscular dystrophy type 2J;C1858763:Dilated cardiomyopathy 1G Benign:1

Aug 18, 2023

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Likely benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
PhyloP100		1.5

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: rs201990196; hg19: chr2-179631357;