NM_024753.5:c.2742C>T

Variant names:

Variant summary

Our verdict is Benign. The variant received -18 ACMG points: 0P and 18B. BP4_ModerateBP6_Very_StrongBS1BS2

The NM_024753.5(TTC21B):c.2742C>T(p.Cys914Cys) variant causes a synonymous change. The variant allele was found at a frequency of 0.00187 in 1,613,642 control chromosomes in the GnomAD database, including 56 homozygotes. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Benign (★★).

Frequency

Genomes: 𝑓 0.0099 ( 33 hom., cov: 32)

Exomes 𝑓: 0.0010 ( 23 hom. )

Consequence

TTC21B
NM_024753.5 synonymous

Scores

Clinical Significance

Benign criteria provided, multiple submitters, no conflicts B:11

Conservation

PhyloP100: 4.37

Publications

4 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: Benign. The variant received -18 ACMG points.

BP4

Computational evidence support a benign effect (BayesDel_noAF=-0.46).

BP6

Variant 2-165901737-G-A is Benign according to our data. Variant chr2-165901737-G-A is described in ClinVar as Benign. ClinVar VariationId is 130654.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

BS1

Variant frequency is greater than expected in population afr. GnomAd4 allele frequency = 0.00993 (1512/152194) while in subpopulation AFR AF = 0.034 (1410/41520). AF 95% confidence interval is 0.0325. There are 33 homozygotes in GnomAd4. There are 746 alleles in the male GnomAd4 subpopulation. Median coverage is 32. This position passed quality control check.

BS2

High Homozygotes in GnomAd4 at 33 AR,AD gene

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
TTC21B	NM_024753.5 link	c.2742C>T	p.Cys914Cys	synonymous_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.2742C>T	p.Cys914Cys	synonymous_variant	Exon 20 of 29	1	NM_024753.5	ENSP00000243344.7		Q7Z4L5-1

Frequencies

GnomAD3 genomes

AF:

0.00992

AC:

1509

AN:

152076

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.0340

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.00471

Gnomad ASJ

AF:

0.00

Gnomad EAS

AF:

0.00

Gnomad SAS

AF:

0.000415

Gnomad FIN

AF:

0.00

Gnomad MID

AF:

0.00316

Gnomad NFE

AF:

0.000147

Gnomad OTH

AF:

0.00814

GnomAD2 exomes

AF:

0.00248

AC:

624

AN:

251234

AF XY:

0.00188

show subpopulations

Gnomad AFR exome

AF:

0.0324

Gnomad AMR exome

AF:

0.00191

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.00

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.000185

Gnomad OTH exome

AF:

0.00131

GnomAD4 exome

AF:

0.00103

AC:

1501

AN:

1461448

Hom.:

Cov.:

AF XY:

0.000904

AC XY:

657

AN XY:

727044

show subpopulations

African (AFR)

AF:

0.0332

AC:

1112

AN:

33472

American (AMR)

AF:

0.00221

AC:

AN:

44724

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26128

East Asian (EAS)

AF:

0.00

AC:

AN:

39680

South Asian (SAS)

AF:

0.000278

AC:

AN:

86244

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53410

Middle Eastern (MID)

AF:

0.00225

AC:

AN:

5768

European-Non Finnish (NFE)

AF:

0.000101

AC:

112

AN:

1111646

Other (OTH)

AF:

0.00234

AC:

141

AN:

60376

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.459

Heterozygous variant carriers

153

230

306

383

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Exome Het

Exome Hom

Variant carriers

126

168

210

<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:

0.00993

AC:

1512

AN:

152194

Hom.:

Cov.:

AF XY:

0.0100

AC XY:

746

AN XY:

74410

show subpopulations

African (AFR)

AF:

0.0340

AC:

1410

AN:

41520

American (AMR)

AF:

0.00471

AC:

AN:

15292

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3470

East Asian (EAS)

AF:

0.00

AC:

AN:

5176

South Asian (SAS)

AF:

0.000416

AC:

AN:

4810

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10594

Middle Eastern (MID)

AF:

0.00340

AC:

AN:

294

European-Non Finnish (NFE)

AF:

0.000147

AC:

AN:

68016

Other (OTH)

AF:

0.00806

AC:

AN:

2110

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.503

Heterozygous variant carriers

140

211

281

351

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Genome Het

Genome Hom

Variant carriers

100

<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:

0.00861

Hom.:

Bravo

AF:

0.0115

Asia WGS

AF:

0.00173

AC:

AN:

3478

EpiCase

AF:

0.000273

EpiControl

AF:

0.000296

ClinVar

Significance: Benign

Submissions summary: Benign:11

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

not specified

Benign:4

Genetic Services Laboratory, University of Chicago

Significance:Likely benign

Review Status:no assertion criteria provided

Collection Method:clinical testing

Likely benign based on allele frequency in 1000 Genomes Project or ESP global frequency and its presence in a patient with a rare or unrelated disease phenotype. NOT Sanger confirmed. -

PreventionGenetics, part of Exact Sciences

Significance:Benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Genome Diagnostics Laboratory, University Medical Center Utrecht

Significance:Benign

Review Status:no assertion criteria provided

Collection Method:clinical testing

- -

Nov 25, 2016

GeneDx

Significance:Benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

This variant is considered likely benign or benign based on one or more of the following criteria: it is a conservative change, it occurs at a poorly conserved position in the protein, it is predicted to be benign by multiple in silico algorithms, and/or has population frequency not consistent with disease. -

not provided

Benign:3

Sep 21, 2023

ARUP Laboratories, Molecular Genetics and Genomics, ARUP Laboratories

Significance:Benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Breakthrough Genomics, Breakthrough Genomics

Significance:Benign

Review Status:criteria provided, single submitter

Collection Method:not provided

- -

Clinical Genetics DNA and cytogenetics Diagnostics Lab, Erasmus MC, Erasmus Medical Center

Significance:Likely benign

Review Status:no assertion criteria provided

Collection Method:clinical testing

- -

Asphyxiating thoracic dystrophy 4

Benign:1

Jan 13, 2018

Illumina Laboratory Services, Illumina

Significance:Benign

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 and internal cut-off values, a variant classified as benign is not then subjected to further curation. The score for this variant resulted in a classification of benign for this disease. -

Jeune thoracic dystrophy;C0687120:Nephronophthisis

Benign:1

Feb 03, 2025

Labcorp Genetics (formerly Invitae), Labcorp

Significance:Benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Nephronophthisis 12

Benign:1

Jan 13, 2018

Illumina Laboratory Services, Illumina

Significance:Benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Connective tissue disorder

Benign:1

May 01, 2020

Genome Diagnostics Laboratory, The Hospital for Sick Children

Significance:Benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

BayesDel_noAF

Benign

-0.46

CADD

Benign

8.5

(source)

DANN

Benign

0.48

PhyloP100

4.4

Mutation Taster

=100/0

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