Variant rs760830696 details in Genebe, Genetics Data Aggregator

Variant summary

Our verdict is Pathogenic. Variant got 18 ACMG points: 18P and 0B. PVS1PM2PP5_Very_Strong

The ENST00000303372.7(TCTN2):c.703del(p.Leu235CysfsTer52) variant causes a frameshift change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000217 in 1,614,078 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Likely pathogenic (★★). Variant results in nonsense mediated mRNA decay.

Frequency

Genomes: 𝑓 0.000020 ( 0 hom., cov: 32)

Exomes 𝑓: 0.000022 ( 0 hom. )

Consequence

TCTN2
ENST00000303372.7 frameshift

Scores

Not classified

Clinical Significance

Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:5

Conservation

PhyloP100: 1.59

Variant links:

Genes affected

TCTN2 (HGNC:25774): (tectonic family member 2) This gene encodes a type I membrane protein that belongs to the tectonic family. Studies in mice suggest that this protein may be involved in hedgehog signaling, and essential for ciliogenesis. Mutations in this gene are associated with Meckel syndrome type 8. Alternatively spliced transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq, Oct 2011]

TCTN2 links:

Genome browser will be placed here

ACMG classification

Classification made for transcript

Verdict is Pathogenic. Variant got 18 ACMG points.

PVS1

Loss of function variant, product undergoes nonsense mediated mRNA decay. LoF is a known mechanism of disease.

PM2

Very rare variant in population databases, with high coverage;

PP5

Variant 12-123686973-TC-T is Pathogenic according to our data. Variant chr12-123686973-TC-T is described in ClinVar as [Likely_pathogenic]. Clinvar id is 212389.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
TCTN2	NM_024809.5 linkuse as main transcript	c.703del	p.Leu235CysfsTer52	frameshift_variant	6/18	ENST00000303372.7	NP_079085.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
TCTN2	ENST00000303372.7 linkuse as main transcript	c.703del	p.Leu235CysfsTer52	frameshift_variant	6/18	1	NM_024809.5	ENSP00000304941	P4	Q96GX1-1

Frequencies

GnomAD3 genomes

AF:

0.0000197

AC:

AN:

152186

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.0000482

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.00

Gnomad ASJ

AF:

0.00

Gnomad EAS

AF:

0.00

Gnomad SAS

AF:

0.00

Gnomad FIN

AF:

0.00

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.0000147

Gnomad OTH

AF:

0.00

GnomAD4 exome

AF:

0.0000219

AC:

AN:

1461892

Hom.:

Cov.:

AF XY:

0.0000138

AC XY:

AN XY:

727248

show subpopulations

Gnomad4 AFR exome

AF:

0.0000299

Gnomad4 AMR exome

AF:

0.00

Gnomad4 ASJ exome

AF:

0.00

Gnomad4 EAS exome

AF:

0.00

Gnomad4 SAS exome

AF:

0.00

Gnomad4 FIN exome

AF:

0.00

Gnomad4 NFE exome

AF:

0.0000279

Gnomad4 OTH exome

AF:

0.00

GnomAD4 genome

AF:

0.0000197

AC:

AN:

152186

Hom.:

Cov.:

AF XY:

0.0000135

AC XY:

AN XY:

74338

show subpopulations

Gnomad4 AFR

AF:

0.0000482

Gnomad4 AMR

AF:

0.00

Gnomad4 ASJ

AF:

0.00

Gnomad4 EAS

AF:

0.00

Gnomad4 SAS

AF:

0.00

Gnomad4 FIN

AF:

0.00

Gnomad4 NFE

AF:

0.0000147

Gnomad4 OTH

AF:

0.00

Bravo

AF:

0.0000151

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:5

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

Meckel-Gruber syndrome;C0431399:Familial aplasia of the vermis

Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Sep 05, 2023

For these reasons, this variant has been classified as Pathogenic. ClinVar contains an entry for this variant (Variation ID: 212389). This variant has not been reported in the literature in individuals affected with TCTN2-related conditions. This variant is present in population databases (rs760830696, gnomAD 0.007%). This sequence change creates a premature translational stop signal (p.Leu235Cysfs*52) in the TCTN2 gene. It is expected to result in an absent or disrupted protein product. Loss-of-function variants in TCTN2 are known to be pathogenic (PMID: 21565611). -

Joubert syndrome 24

Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Johns Hopkins Genomics, Johns Hopkins University

Jan 13, 2021

This TCTN2 variant is absent in a large population dataset and has an entry in ClinVar. This 1-bp deletion results in a frameshift in exon 6 of 18 that is predicted to introduce a premature termination codon (PTC), likely leading to nonsense-mediated decay and lack of protein production. This variant alone is not expected to cause Meckel syndrome 8. We consider c.703delC to be pathogenic. -

Meckel syndrome, type 8

Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Genetic Services Laboratory, University of Chicago

Feb 19, 2015

- -

not provided

Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

GeneDx

Jul 08, 2016

The c.703delC pathogenic variant in the TCTN2 gene causes a frameshift starting with codon Leucine 235, changes this amino acid to a Cysteine residue and creates a premature Stop codon at position 52 of the new reading frame, denoted p.L235CfsX52. This pathogenic variant is predicted to cause loss of normal protein function either through protein truncation or nonsense-mediated mRNA decay. It was not observed with any significant frequency in approximately 6,500 individuals of European and African American ancestry in the NHLBI Exome Sequencing Project, indicating it is not a common benign variant in these populations. Although this variant has not been previously reported to our knowledge, it is interpreted as a pathogenic variant. -

Joubert syndrome and related disorders

Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Women's Health and Genetics/Laboratory Corporation of America, LabCorp

Dec 27, 2022

Variant summary: TCTN2 c.703delC (p.Leu235CysfsX52) results in a premature termination codon, predicted to cause a truncation of the encoded protein or absence of the protein due to nonsense mediated decay, which are commonly known mechanisms for disease. Truncations downstream of this position have been reported in affected individuals (HGMD). The variant was absent in 251488 control chromosomes (gnomAD). To our knowledge, no occurrence of c.703delC in individuals affected with Joubert Syndrome and Related Disorders and no experimental evidence demonstrating its impact on protein function have been reported. Three clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar after 2014 without evidence for independent evaluation, and all of them classified the variant as pathogenic. Based on the evidence outlined above, the variant was classified as likely pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

Splicing

Name

Calibrated prediction

Score

Prediction

SpliceAI score (max)

0.030

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

Below is the list of publications found by LitVar. It may be empty.

Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

LitVar

Other links and lift over