2-165945681-G-T

Variant summary

Our verdict is Uncertain significance. Variant got 2 ACMG points: 2P and 0B. PM2

The NM_024753.5(TTC21B):c.272C>A(p.Ala91Asp) variant causes a missense change. The variant allele was found at a frequency of 0.000135 in 1,612,852 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Uncertain significance (★★).

Frequency

Genomes: 𝑓 0.00014 ( 0 hom., cov: 32)

Exomes 𝑓: 0.00013 ( 0 hom. )

Consequence

TTC21B
NM_024753.5 missense

Scores

Clinical Significance

Uncertain significance criteria provided, multiple submitters, no conflicts U:3

Conservation

PhyloP100: 4.68

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 made for transcript

Verdict is Uncertain_significance. Variant got 2 ACMG points.

PM2

Very rare variant in population databases, with high coverage;

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
TTC21B	NM_024753.5 linkuse as main transcript	c.272C>A	p.Ala91Asp	missense_variant	4/29	ENST00000243344.8
TTC21B-AS1	NR_038983.1 linkuse as main transcript	n.277-1516G>T		intron_variant, non_coding_transcript_variant

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
TTC21B	ENST00000243344.8 linkuse as main transcript	c.272C>A	p.Ala91Asp	missense_variant	4/29	1	NM_024753.5	P1	Q7Z4L5-1
TTC21B-AS1	ENST00000440322.5 linkuse as main transcript	n.221-1516G>T		intron_variant, non_coding_transcript_variant		4

Frequencies

GnomAD3 genomes

AF:

0.000138

AC:

AN:

152108

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.0000483

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:

0.000279

Gnomad OTH

AF:

0.00

GnomAD3 exomes

AF:

0.0000757

AC:

AN:

250976

Hom.:

AF XY:

0.0000884

AC XY:

AN XY:

135696

show subpopulations

Gnomad AFR exome

AF:

0.0000615

Gnomad AMR exome

AF:

0.0000290

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.00

Gnomad SAS exome

AF:

0.00

Gnomad FIN exome

AF:

0.0000468

Gnomad NFE exome

AF:

0.000141

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.000135

AC:

197

AN:

1460744

Hom.:

Cov.:

AF XY:

0.000121

AC XY:

AN XY:

726690

show subpopulations

Gnomad4 AFR exome

AF:

0.0000299

Gnomad4 AMR exome

AF:

0.0000224

Gnomad4 ASJ exome

AF:

0.00

Gnomad4 EAS exome

AF:

0.00

Gnomad4 SAS exome

AF:

0.00

Gnomad4 FIN exome

AF:

0.0000189

Gnomad4 NFE exome

AF:

0.000169

Gnomad4 OTH exome

AF:

0.0000994

GnomAD4 genome

AF:

0.000138

AC:

AN:

152108

Hom.:

Cov.:

AF XY:

0.000121

AC XY:

AN XY:

74318

show subpopulations

Gnomad4 AFR

AF:

0.0000483

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:

0.000279

Gnomad4 OTH

AF:

0.00

Alfa

AF:

0.000202

Hom.:

Bravo

AF:

0.000132

TwinsUK

AF:

0.000270

AC:

ALSPAC

AF:

0.000259

AC:

ESP6500AA

AF:

0.00

AC:

ESP6500EA

AF:

0.000233

AC:

ExAC

AF:

0.0000741

AC:

EpiCase

AF:

0.000109

EpiControl

AF:

0.000415

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:3

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

Asphyxiating thoracic dystrophy 4;C3151186:Nephronophthisis 12

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Fulgent Genetics, Fulgent Genetics

Feb 19, 2022

- -

Jeune thoracic dystrophy;C0687120:Nephronophthisis

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

Sep 06, 2022

This sequence change replaces alanine, which is neutral and non-polar, with aspartic acid, which is acidic and polar, at codon 91 of the TTC21B protein (p.Ala91Asp). This variant is present in population databases (rs371376632, gnomAD 0.01%). 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: 411950). Algorithms developed to predict the effect of missense changes on protein structure and function are either unavailable or do not agree on the potential impact of this missense change (SIFT: "Deleterious"; PolyPhen-2: "Possibly Damaging"; Align-GVGD: "Class C0"). 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. -

TTC21B-related disorder

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

PreventionGenetics, part of Exact Sciences

Dec 14, 2023

The TTC21B c.272C>A variant is predicted to result in the amino acid substitution p.Ala91Asp. To our knowledge, this variant has not been reported in the literature. This variant is reported in 0.014% 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

Uncertain

0.40

BayesDel_addAF

Benign

-0.13

BayesDel_noAF

Benign

-0.19

Cadd

Pathogenic

Dann

Uncertain

1.0

DEOGEN2

Uncertain

0.60

Eigen

Uncertain

0.65

Eigen_PC

Uncertain

0.66

FATHMM_MKL

Uncertain

0.96

LIST_S2

Uncertain

0.86

M_CAP

Benign

0.040

MetaRNN

Uncertain

0.68

MetaSVM

Benign

-0.41

MutationAssessor

Uncertain

2.9

MutationTaster

Benign

1.0

PrimateAI

Benign

0.47

PROVEAN

Pathogenic

-4.6

REVEL

Benign

0.25

Sift

Uncertain

0.0030

Sift4G

Uncertain

0.0070

Polyphen

0.85

Vest4

0.68

MVP

0.45

MPC

0.21

ClinPred

0.92

GERP RS

5.5

RBP_binding_hub_radar

0.0

RBP_regulation_power_radar

1.7

Varity_R

0.66

gMVP

0.64

Splicing

Name

Calibrated prediction

Score

Prediction

SpliceAI score (max)

0.060

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