NM_024753.5:c.2693G>A

Variant names:

Variant summary

Our verdict is Uncertain significance. The variant received 0 ACMG points: 0P and 0B.

The NM_024753.5(TTC21B):c.2693G>A(p.Arg898Gln) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000948 in 1,613,962 control chromosomes in the GnomAD database, with no homozygous occurrence. 13/22 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★★).

Frequency

Genomes: 𝑓 0.000066 ( 0 hom., cov: 32)

Exomes 𝑓: 0.000098 ( 0 hom. )

Consequence

TTC21B
NM_024753.5 missense

Scores

Clinical Significance

Uncertain significance criteria provided, multiple submitters, no conflicts P:1U:5

Conservation

PhyloP100: 3.40

Publications

1 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 Gene-Disease associations (from GenCC):

nephronophthisis 12
Inheritance: AD, AR Classification: DEFINITIVE, STRONG, LIMITED Submitted by: Ambry Genetics, ClinGen, Labcorp Genetics (formerly Invitae)
asphyxiating thoracic dystrophy 4
Inheritance: AR Classification: DEFINITIVE, STRONG Submitted by: Ambry Genetics, Labcorp Genetics (formerly Invitae)
Jeune syndrome
Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
nephronophthisis 2
Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet

TTC21B links:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Uncertain_significance. The variant received 0 ACMG points.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
TTC21B	NM_024753.5 link	c.2693G>A	p.Arg898Gln	missense_variant	Exon 20 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.2693G>A	p.Arg898Gln	missense_variant	Exon 20 of 29	1	NM_024753.5	ENSP00000243344.7		Q7Z4L5-1

Frequencies

GnomAD3 genomes

AF:

0.0000657

AC:

AN:

152132

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.0000483

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.0000655

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:

0.000103

Gnomad OTH

AF:

0.00

GnomAD2 exomes

AF:

0.0000398

AC:

AN:

251350

AF XY:

0.0000294

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.0000289

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.00

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.0000792

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.0000978

AC:

143

AN:

1461830

Hom.:

Cov.:

AF XY:

0.0000921

AC XY:

AN XY:

727218

show subpopulations

African (AFR)

AF:

0.0000299

AC:

AN:

33480

American (AMR)

AF:

0.0000447

AC:

AN:

44724

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26132

East Asian (EAS)

AF:

0.00

AC:

AN:

39676

South Asian (SAS)

AF:

0.00

AC:

AN:

86256

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53414

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5768

European-Non Finnish (NFE)

AF:

0.000112

AC:

124

AN:

1111990

Other (OTH)

AF:

0.000265

AC:

AN:

60390

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.468

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Exome Het

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

GnomAD4 genome

AF:

0.0000657

AC:

AN:

152132

Hom.:

Cov.:

AF XY:

0.0000404

AC XY:

AN XY:

74290

show subpopulations

African (AFR)

AF:

0.0000483

AC:

AN:

41426

American (AMR)

AF:

0.0000655

AC:

AN:

15272

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3470

East Asian (EAS)

AF:

0.00

AC:

AN:

5190

South Asian (SAS)

AF:

0.00

AC:

AN:

4834

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10588

Middle Eastern (MID)

AF:

0.00

AC:

AN:

316

European-Non Finnish (NFE)

AF:

0.000103

AC:

AN:

68032

Other (OTH)

AF:

0.00

AC:

AN:

2092

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.500

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Genome Het

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

Alfa

AF:

0.0000772

Hom.:

Bravo

AF:

0.0000378

ExAC

AF:

0.0000330

AC:

EpiCase

AF:

0.000109

EpiControl

AF:

0.0000593

ClinVar

Significance: Uncertain significance

Submissions summary: Pathogenic:1Uncertain:5

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

Jeune thoracic dystrophy

Pathogenic:1Uncertain:1

University of Washington Center for Mendelian Genomics, University of Washington

Significance:Likely pathogenic

Review Status:no assertion criteria provided

Collection Method:research

- -

Jun 01, 2017

Dan Cohn Lab, University Of California Los Angeles

Significance:Uncertain significance

Review Status:no assertion criteria provided

Collection Method:research

- -

Jeune thoracic dystrophy;C0687120:Nephronophthisis

Uncertain:1

Aug 17, 2022

Labcorp Genetics (formerly Invitae), Labcorp

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

This sequence change replaces arginine, which is basic and polar, with glutamine, which is neutral and polar, at codon 898 of the TTC21B protein (p.Arg898Gln). This variant is present in population databases (rs574017249, gnomAD 0.008%). This missense change has been observed in individual(s) with asphyxiating thoracic dystrophy (PMID: 29068549). ClinVar contains an entry for this variant (Variation ID: 446691). Algorithms developed to predict the effect of missense changes on protein structure and function output the following: SIFT: "Deleterious"; PolyPhen-2: "Benign"; Align-GVGD: "Class C35". The glutamine amino acid residue is found in multiple mammalian species, which suggests that this missense change does not adversely affect protein function. In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. -

Asphyxiating thoracic dystrophy 4

Uncertain:1

Jan 13, 2018

Illumina Laboratory Services, Illumina

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

This variant was observed in the ICSL laboratory as part of a predisposition screen in an ostensibly healthy population. It had not been previously curated by ICSL or reported in the Human Gene Mutation Database (HGMD: prior to June 1st, 2018), and was therefore a candidate for classification through an automated scoring system. Utilizing variant allele frequency, disease prevalence and penetrance estimates, and inheritance mode, an automated score was calculated to assess if this variant is too frequent to cause the disease. Based on the score, this variant could not be ruled out of causing disease and therefore its association with disease required further investigation. A literature search was performed for the gene, cDNA change, and amino acid change (if applicable). No publications were found based on this search. This variant was therefore classified as a variant of unknown significance for this disease. -

Nephronophthisis 12

Uncertain:1

Jan 13, 2018

Illumina Laboratory Services, Illumina

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

TTC21B-related disorder

Uncertain:1

Aug 06, 2024

PreventionGenetics, part of Exact Sciences

Significance:Uncertain significance

Review Status:no assertion criteria provided

Collection Method:clinical testing

The TTC21B c.2693G>A variant is predicted to result in the amino acid substitution p.Arg898Gln. This variant has been reported in an individual with asphyxiating thoracic dystrophy who also carries a missense change in DYNC2H1 (Table S3. Zhang et al 2018. PubMed ID: 29068549). This variant is reported in 0.0093% of alleles in individuals of European (Non-Finnish) descent in gnomAD. At this time, the clinical significance of this variant is uncertain due to the absence of conclusive functional and genetic evidence. -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Benign

0.083

BayesDel_addAF

Benign

-0.19

BayesDel_noAF

Benign

-0.33

CADD

Benign

(source)

DANN

Pathogenic

1.0

DEOGEN2

Benign

0.38

Eigen

Uncertain

0.20

Eigen_PC

Uncertain

0.25

FATHMM_MKL

Uncertain

0.94

LIST_S2

Benign

0.78

M_CAP

Benign

0.016

MetaRNN

Uncertain

0.55

MetaSVM

Benign

-0.88

MutationAssessor

Pathogenic

3.0

PhyloP100

3.4

PrimateAI

Benign

0.27

PROVEAN

Benign

-2.1

REVEL

Benign

0.19

Sift

Benign

0.043

Sift4G

Uncertain

0.051

Polyphen

0.56

Vest4

0.41

MutPred

0.78

Loss of MoRF binding (P = 0.0635);

MVP

0.35

MPC

0.050

ClinPred

0.37

GERP RS

3.9

Varity_R

0.21

gMVP

0.22

Mutation Taster

=86/14

polymorphism

(source)

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

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Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

Publications

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

Age Distribution

Age Distribution

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

Other links and lift over