NM_017752.3:c.427G>A

Variant names:

Variant summary

Our verdict is Benign. Variant got -7 ACMG points: 0P and 7B. BP4_ModerateBS1_SupportingBS2

The NM_017752.3(TBC1D8B):c.427G>A(p.Ala143Thr) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.0000389 in 1,209,033 control chromosomes in the GnomAD database, with no homozygous occurrence. There are 12 hemizygotes in GnomAD. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★).

Frequency

Genomes: 𝑓 0.00021 ( 0 hom., 7 hem., cov: 23)

Exomes 𝑓: 0.000022 ( 0 hom. 5 hem. )

Consequence

TBC1D8B
NM_017752.3 missense

Scores

Clinical Significance

Uncertain significance criteria provided, single submitter U:1B:1

Conservation

PhyloP100: 8.10

Variant links:

Genes affected

TBC1D8B (HGNC:24715): (TBC1 domain family member 8B) This gene encodes a protein with a TBC (Tre-2/Bub2/CDC16) domain. Some mammalian proteins with this domain have been shown to function as Rab-GAPs by binding to specific Rab proteins and affecting their GTPase activity. Alternative splicing results in multiple transcript variants. [provided by RefSeq, Sep 2011]

TBC1D8B links:

MORC4 (HGNC:23485): (MORC family CW-type zinc finger 4) In human, the four current members of the microrchidia (morc) gene family share an N-terminal ATPase-like ATP-binding region and a CW four-cysteine zinc-finger motif. The protein encoded by this gene also has a nuclear matrix binding domain and a two-stranded coiled-coil motif near its C-terminus. This gene is widely expressed at low levels in normal tissues and has elevated expression in placenta and testis. Alternative splicing results in multiple transcript variants encoding distinct proteins. [provided by RefSeq, Jan 2010]

MORC4 links:

Genome browser will be placed here

ACMG classification

Classification made for transcript

Verdict is Benign. Variant got -7 ACMG points.

BP4

Computational evidence support a benign effect (MetaRNN=0.11819044).

BS1

Variant frequency is greater than expected in population afr. gnomad4 allele frequency = 0.000206 (23/111747) while in subpopulation AFR AF= 0.000746 (23/30840). AF 95% confidence interval is 0.000509. There are 0 homozygotes in gnomad4. There are 7 alleles in male gnomad4 subpopulation. Median coverage is 23. This position pass quality control queck. Existence of Clinvar submissions makes me limit the strength of this signal to Supporting

BS2

High Hemizygotes in GnomAd4 at 7 XL gene

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
TBC1D8B	NM_017752.3 link	c.427G>A	p.Ala143Thr	missense_variant	Exon 4 of 21	ENST00000357242.10	NP_060222.2	Q0IIM8-1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
TBC1D8B	ENST00000357242.10 link	c.427G>A	p.Ala143Thr	missense_variant	Exon 4 of 21	1	NM_017752.3	ENSP00000349781.5		Q0IIM8-1

Frequencies

GnomAD3 genomes

AF:

0.000206

AC:

AN:

111747

Hom.:

Cov.:

AF XY:

0.000206

AC XY:

AN XY:

33993

show subpopulations

Gnomad AFR

AF:

0.000746

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:

0.00

Gnomad OTH

AF:

0.00

GnomAD3 exomes

AF:

0.0000547

AC:

AN:

182761

Hom.:

AF XY:

0.0000148

AC XY:

AN XY:

67435

show subpopulations

Gnomad AFR exome

AF:

0.000762

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:

0.00

Gnomad NFE exome

AF:

0.00

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.0000219

AC:

AN:

1097286

Hom.:

Cov.:

AF XY:

0.0000138

AC XY:

AN XY:

363058

show subpopulations

Gnomad4 AFR exome

AF:

0.000911

Gnomad4 AMR exome

AF:

0.00

Gnomad4 ASJ exome

AF:

0.00

Gnomad4 EAS exome

AF:

0.00

Gnomad4 SAS exome

AF:

0.00

Gnomad4 FIN exome

AF:

0.00

Gnomad4 NFE exome

AF:

0.00

Gnomad4 OTH exome

AF:

0.00

GnomAD4 genome

AF:

0.000206

AC:

AN:

111747

Hom.:

Cov.:

AF XY:

0.000206

AC XY:

AN XY:

33993

show subpopulations

Gnomad4 AFR

AF:

0.000746

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:

0.00

Gnomad4 OTH

AF:

0.00

Alfa

AF:

0.000241

Hom.:

Bravo

AF:

0.000246

ESP6500AA

AF:

0.00104

AC:

ESP6500EA

AF:

0.00

AC:

ExAC

AF:

0.0000577

AC:

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1Benign:1

Revision: criteria provided, single submitter

LINK: link

Submissions by phenotype

not provided

Uncertain:1

Jul 05, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces alanine, which is neutral and non-polar, with threonine, which is neutral and polar, at codon 143 of the TBC1D8B protein (p.Ala143Thr). This variant is present in population databases (rs141400138, gnomAD 0.06%), and has an allele count higher than expected for a pathogenic variant. This variant has not been reported in the literature in individuals affected with TBC1D8B-related conditions. ClinVar contains an entry for this variant (Variation ID: 2073080). Algorithms developed to predict the effect of missense changes on protein structure and function output the following: SIFT: "Not Available"; PolyPhen-2: "Possibly Damaging"; Align-GVGD: "Not Available". The threonine 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. -

TBC1D8B-related disorder

Benign:1

Dec 04, 2023

PreventionGenetics, part of Exact Sciences

Significance: Likely benign

Review Status: no assertion criteria provided

Collection Method: clinical testing

This variant is classified as likely benign based on ACMG/AMP sequence variant interpretation guidelines (Richards et al. 2015 PMID: 25741868, with internal and published modifications). -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Benign

0.23

BayesDel_addAF

Benign

-0.46

BayesDel_noAF

Benign

-0.54

CADD

Benign

DANN

Uncertain

0.99

DEOGEN2

Benign

0.25

T;.;T;T

FATHMM_MKL

Pathogenic

0.98

LIST_S2

Uncertain

0.88

D;D;D;D

M_CAP

Benign

0.025

MetaRNN

Benign

0.12

T;T;T;T

MetaSVM

Benign

-1.1

MutationAssessor

Uncertain

2.1

M;M;.;.

PrimateAI

Uncertain

0.50

PROVEAN

Uncertain

-3.0

D;D;D;D

REVEL

Benign

0.15

Sift

Benign

0.042

D;D;D;D

Sift4G

Uncertain

0.041

D;T;T;D

Polyphen

0.12

B;.;B;.

Vest4

0.26

MVP

0.52

MPC

0.23

ClinPred

0.30

GERP RS

3.9

Varity_R

0.32

gMVP

0.63

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