dbSNP rs777162250: TTC21B:p.Trp228* (chr2-165941053-C-T) – ACMG Classification: Pathogenic (12 pts)

Variant summary

Our verdict is Pathogenic. The variant received 12 ACMG points: 12P and 0B. PVS1PM2PP5_Moderate

The NM_024753.5(TTC21B):c.684G>A(p.Trp228*) variant causes a stop gained change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.000000684 in 1,461,644 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Pathogenic (★). Variant results in nonsense mediated mRNA decay.

Frequency

Genomes: not found (cov: 33)

Exomes 𝑓: 6.8e-7 ( 0 hom. )

Consequence

TTC21B
NM_024753.5 stop_gained

Scores

Clinical Significance

Pathogenic criteria provided, single submitter P:1

Conservation

PhyloP100: 7.91

Publications

0 publications found

Variant links:

Genes affected

TTC21B (HGNC:25660): (tetratricopeptide repeat domain 21B) This gene encodes a member of TTC21 family, containing several tetratricopeptide repeat (TPR) domains. This protein is localized to the cilium axoneme, and may play a role in retrograde intraflagellar transport in cilia. Mutations in this gene are associated with various ciliopathies, nephronophthisis 12, and asphyxiating thoracic dystrophy 4. [provided by RefSeq, Oct 2011]

TTC21B links:

TTC21B-AS1 (HGNC:41115): (TTC21B antisense RNA 1)

TTC21B-AS1 links:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Pathogenic. The variant received 12 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 2-165941053-C-T is Pathogenic according to our data. Variant chr2-165941053-C-T is described in ClinVar as Pathogenic. ClinVar VariationId is 216125.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
TTC21B	NM_024753.5 link	c.684G>A	p.Trp228*	stop_gained	Exon 6 of 29	ENST00000243344.8	NP_079029.3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
TTC21B	ENST00000243344.8 link	c.684G>A	p.Trp228*	stop_gained	Exon 6 of 29	1	NM_024753.5	ENSP00000243344.7

Frequencies

GnomAD3 genomes

Cov.:

GnomAD2 exomes

AF:

0.00000796

AC:

AN:

251284

AF XY:

0.0000147

show subpopulations

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:

0.0000176

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

6.84e-7

AC:

AN:

1461644

Hom.:

Cov.:

AF XY:

0.00000138

AC XY:

AN XY:

727124

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

33468

American (AMR)

AF:

0.00

AC:

AN:

44706

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26122

East Asian (EAS)

AF:

0.00

AC:

AN:

39686

South Asian (SAS)

AF:

0.00

AC:

AN:

86252

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53416

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5768

European-Non Finnish (NFE)

AF:

8.99e-7

AC:

AN:

1111836

Other (OTH)

AF:

0.00

AC:

AN:

60390

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.425

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

GnomAD4 genome

Cov.:

Alfa

AF:

0.00000534

Hom.:

ExAC

AF:

0.00000824

AC:

EpiCase

AF:

0.00

EpiControl

AF:

0.0000593

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:1

Revision: criteria provided, single submitter

LINK: link

Submissions by phenotype

Jeune thoracic dystrophy;C0687120:Nephronophthisis

Pathogenic:1

Aug 10, 2023

Labcorp Genetics (formerly Invitae), Labcorp

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

This sequence change creates a premature translational stop signal (p.Trp228*) in the TTC21B gene. It is expected to result in an absent or disrupted protein product. Loss-of-function variants in TTC21B are known to be pathogenic (PMID: 18327258, 21068128, 21258341, 23559409, 24876116, 25492405, 27491411, 29068549). This variant is present in population databases (rs777162250, gnomAD 0.002%). This variant has not been reported in the literature in individuals affected with TTC21B-related conditions. ClinVar contains an entry for this variant (Variation ID: 216125). For these reasons, this variant has been classified as Pathogenic.

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

BayesDel_addAF

Pathogenic

0.61

BayesDel_noAF

Pathogenic

0.66

CADD

Pathogenic

(source)

DANN

Uncertain

1.0

Eigen

Pathogenic

0.96

Eigen_PC

Pathogenic

0.84

FATHMM_MKL

Pathogenic

1.0

PhyloP100

7.9

Vest4

0.38

GERP RS

5.2

RBP_binding_hub_radar

0.0

RBP_regulation_power_radar

1.7

Mutation Taster

=16/184

disease causing (ClinVar)

(source)

Splicing

Name

Calibrated prediction

Score

Prediction

SpliceAI score (max)

0.090

Details are displayed if max score is > 0.2

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

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Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

Publications

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

Other links and lift over