Genetic Variant TTC21B:p.Glu550Glu (chr2-165919300-T-C) – ACMG Classification: Benign (-10 pts)

Variant summary

Our verdict is Benign. Variant got -10 ACMG points: 0P and 10B. BP4_StrongBP6BP7BS2

The NM_024753.5(TTC21B):c.1650A>G(p.Glu550Glu) variant causes a synonymous change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00101 in 1,614,064 control chromosomes in the GnomAD database, including 4 homozygotes. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).

Frequency

Genomes: 𝑓 0.00050 ( 0 hom., cov: 32)

Exomes 𝑓: 0.0011 ( 4 hom. )

Consequence

TTC21B
NM_024753.5 synonymous

Scores

Clinical Significance

Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:2B:4

Conservation

PhyloP100: 1.93

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:

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ACMG classification

Classification made for transcript

Verdict is Benign. Variant got -10 ACMG points.

BP4

Computational evidence support a benign effect (BayesDel_noAF=-0.56).

BP6

Variant 2-165919300-T-C is Benign according to our data. Variant chr2-165919300-T-C is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 261767.We mark this variant Likely_benign, oryginal submissions are: {Likely_benign=4, Uncertain_significance=2}.

BP7

Synonymous conserved (PhyloP=1.92 with no splicing effect.

BS2

High Homozygotes in GnomAdExome4 at 4 AR gene

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
TTC21B	NM_024753.5 link	c.1650A>G	p.Glu550Glu	synonymous_variant	Exon 13 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.1650A>G	p.Glu550Glu	synonymous_variant	Exon 13 of 29	1	NM_024753.5	ENSP00000243344.7		Q7Z4L5-1

Frequencies

GnomAD3 genomes

AF:

0.000499

AC:

AN:

152158

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.000217

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.000196

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:

0.000941

Gnomad OTH

AF:

0.00

GnomAD3 exomes

AF:

0.000442

AC:

111

AN:

251270

Hom.:

AF XY:

0.000390

AC XY:

AN XY:

135794

show subpopulations

Gnomad AFR exome

AF:

0.000185

Gnomad AMR exome

AF:

0.00

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.00

Gnomad SAS exome

AF:

0.00

Gnomad FIN exome

AF:

0.0000924

Gnomad NFE exome

AF:

0.000907

Gnomad OTH exome

AF:

0.000490

GnomAD4 exome

AF:

0.00106

AC:

1554

AN:

1461788

Hom.:

Cov.:

AF XY:

0.00103

AC XY:

747

AN XY:

727192

show subpopulations

Gnomad4 AFR exome

AF:

0.000149

Gnomad4 AMR exome

AF:

0.0000224

Gnomad4 ASJ exome

AF:

0.00

Gnomad4 EAS exome

AF:

0.00

Gnomad4 SAS exome

AF:

0.0000116

Gnomad4 FIN exome

AF:

0.000168

Gnomad4 NFE exome

AF:

0.00132

Gnomad4 OTH exome

AF:

0.00123

GnomAD4 genome

AF:

0.000499

AC:

AN:

152276

Hom.:

Cov.:

AF XY:

0.000470

AC XY:

AN XY:

74464

show subpopulations

Gnomad4 AFR

AF:

0.000217

Gnomad4 AMR

AF:

0.000196

Gnomad4 ASJ

AF:

0.00

Gnomad4 EAS

AF:

0.00

Gnomad4 SAS

AF:

0.00

Gnomad4 FIN

AF:

0.00

Gnomad4 NFE

AF:

0.000941

Gnomad4 OTH

AF:

0.00

Alfa

AF:

0.000818

Hom.:

Bravo

AF:

0.000601

EpiCase

AF:

0.00125

EpiControl

AF:

0.000711

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:2Benign:4

Revision: criteria provided, conflicting classifications

LINK: link

Submissions by phenotype

not provided

Benign:2

Aug 18, 2023

ARUP Laboratories, Molecular Genetics and Genomics, ARUP Laboratories

Significance: Likely benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Dec 08, 2020

GeneDx

Significance: Likely benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

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

not specified

Benign:1

PreventionGenetics, part of Exact Sciences

Significance: Likely benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Jeune thoracic dystrophy;C0687120:Nephronophthisis

Benign:1

Jan 25, 2025

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Likely 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

-0.56

CADD

Benign

8.0

DANN

Benign

0.67

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

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