Genetic Variant NM_024753.5:c.616G>T (chr2-165941121-C-A) – ACMG Classification: Uncertain_significance (0 pts)

Variant summary

Our verdict is Uncertain significance. The variant received 0 ACMG points: 2P and 2B. PM2BP4_Moderate

The NM_024753.5(TTC21B):c.616G>T(p.Val206Leu) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000000684 in 1,461,604 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 16/22 in silico tools predict a benign outcome for this variant. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar. Another variant affecting the same amino acid position, but resulting in a different missense (i.e. V206M) has been classified as Uncertain significance.

Frequency

Genomes: not found (cov: 33)

Exomes 𝑓: 6.8e-7 ( 0 hom. )

Consequence

TTC21B
NM_024753.5 missense

Scores

Clinical Significance

Not reported in ClinVar

Conservation

PhyloP100: 2.13

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:

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ACMG classification

Classification was made for transcript

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

PM2

Very rare variant in population databases, with high coverage;

BP4

Computational evidence support a benign effect (MetaRNN=0.11956099).

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_024753.5. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein
TTC21B	NM_024753.5	MANE Select	c.616G>T	p.Val206Leu	missense	Exon 6 of 29	NP_079029.3
TTC21B-AS1	NR_038983.1		n.277-6076C>A		intron	N/A
TTC21B-AS1	NR_038984.1		n.221-6076C>A		intron	N/A

Ensembl Transcripts

Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
TTC21B	ENST00000243344.8	TSL:1 MANE Select	c.616G>T	p.Val206Leu	missense	Exon 6 of 29	ENSP00000243344.7	Q7Z4L5-1
TTC21B	ENST00000464374.5	TSL:1	n.656G>T		non_coding_transcript_exon	Exon 6 of 11
TTC21B	ENST00000679840.1		c.616G>T	p.Val206Leu	missense	Exon 6 of 27	ENSP00000505248.1	A0A7P0T8P4

Frequencies

GnomAD3 genomes

Cov.:

GnomAD4 exome

AF:

6.84e-7

AC:

AN:

1461604

Hom.:

Cov.:

AF XY:

0.00000138

AC XY:

AN XY:

727100

show subpopulations

⚠️ The allele balance in gnomAD version 4 Exomes is significantly skewed from the expected value of 0.5.

African (AFR)

AF:

0.00

AC:

AN:

33468

American (AMR)

AF:

0.00

AC:

AN:

44688

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26128

East Asian (EAS)

AF:

0.00

AC:

AN:

39680

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:

8.99e-7

AC:

AN:

1111820

Other (OTH)

AF:

0.00

AC:

AN:

60382

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0), which strongly suggests a high chance of mosaicism in these individuals.

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.325

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

Cov.:

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.9

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Benign

0.29

BayesDel_addAF

Benign

-0.19

BayesDel_noAF

Benign

-0.50

CADD

Benign

(source)

DANN

Uncertain

0.98

DEOGEN2

Benign

0.21

Eigen

Benign

-0.38

Eigen_PC

Benign

-0.37

FATHMM_MKL

Uncertain

0.91

LIST_S2

Uncertain

0.89

M_CAP

Benign

0.023

MetaRNN

Benign

0.12

MetaSVM

Benign

-0.90

MutationAssessor

Benign

1.9

PhyloP100

2.1

PrimateAI

Benign

0.31

PROVEAN

Benign

-2.1

REVEL

Benign

0.13

Sift

Benign

0.087

Sift4G

Uncertain

0.040

Polyphen

0.022

Vest4

0.096

MutPred

0.47

Gain of catalytic residue at V206 (P = 0.1859)

MVP

0.50

MPC

0.034

ClinPred

0.26

GERP RS

0.18

RBP_binding_hub_radar

0.0

RBP_regulation_power_radar

1.1

Varity_R

0.065

gMVP

0.37

Mutation Taster

=90/10

polymorphism

(source)

Splicing

Name

Calibrated prediction

Score

Prediction

SpliceAI score (max)

0.010

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

Variant Effect in Transcripts

RefSeq Transcripts

Ensembl Transcripts

Frequencies

Age Distribution

ClinVar

Computational scores

Splicing

Publications

Other links and lift over