Genetic Variant TBC1D2B:p.Val776Ile (chr15-78009059-C-T) – ACMG Classification: Likely_benign (-4 pts)

Variant summary

Our verdict is Likely benign. Variant got -4 ACMG points: 2P and 6B. PM2BP4_ModerateBS1

The NM_144572.2(TBC1D2B):c.2326G>A(p.Val776Ile) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000155 in 1,608,970 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 13/21 in silico tools predict a benign outcome for this variant. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar.

Frequency

Genomes: 𝑓 0.000039 ( 0 hom., cov: 33)

Exomes 𝑓: 0.000013 ( 0 hom. )

Consequence

TBC1D2B
NM_144572.2 missense

Scores

Clinical Significance

Uncertain significance criteria provided, single submitter U:1

Conservation

PhyloP100: 2.64

Variant links:

Genes affected

TBC1D2B (HGNC:29183): (TBC1 domain family member 2B) Predicted to enable GTPase activator activity. Predicted to be involved in activation of GTPase activity and intracellular protein transport. Located in cytosol. [provided by Alliance of Genome Resources, Apr 2022]

TBC1D2B links:

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ACMG classification

Classification made for transcript

Verdict is Likely_benign. Variant got -4 ACMG points.

PM2

Very rare variant in population databases, with high coverage;

BP4

Computational evidence support a benign effect (MetaRNN=0.14477512).

BS1

Variant frequency is greater than expected in population afr. gnomad4 allele frequency = 0.0000394 (6/152230) while in subpopulation AFR AF= 0.00012 (5/41542). AF 95% confidence interval is 0.0000473. There are 0 homozygotes in gnomad4. There are 2 alleles in male gnomad4 subpopulation. Median coverage is 33. This position pass quality control queck.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
TBC1D2B	NM_144572.2 link	c.2326G>A	p.Val776Ile	missense_variant	Exon 10 of 13	ENST00000300584.8	NP_653173.1	Q9UPU7-1B2RTQ2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	UniProt
TBC1D2B	ENST00000300584.8 link	c.2326G>A	p.Val776Ile	missense_variant	Exon 10 of 13	5	NM_144572.2	ENSP00000300584.3	Q9UPU7-1
TBC1D2B	ENST00000409931.7 link	c.2326G>A	p.Val776Ile	missense_variant	Exon 10 of 13	1		ENSP00000387165.3	Q9UPU7-2
TBC1D2B	ENST00000472786.1 link	n.1292G>A		non_coding_transcript_exon_variant	Exon 3 of 4	2

Frequencies

GnomAD3 genomes

AF:

0.0000394

AC:

AN:

152112

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.000121

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.0000655

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:

0.0000247

AC:

AN:

242536

Hom.:

AF XY:

0.00000765

AC XY:

AN XY:

130664

show subpopulations

Gnomad AFR exome

AF:

0.000260

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:

0.0000183

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.0000130

AC:

AN:

1456740

Hom.:

Cov.:

AF XY:

0.00000967

AC XY:

AN XY:

723938

show subpopulations

Gnomad4 AFR exome

AF:

0.0000898

Gnomad4 AMR exome

AF:

0.00

Gnomad4 ASJ exome

AF:

0.00

Gnomad4 EAS exome

AF:

0.00

Gnomad4 SAS exome

AF:

0.0000118

Gnomad4 FIN exome

AF:

0.00

Gnomad4 NFE exome

AF:

0.0000117

Gnomad4 OTH exome

AF:

0.0000332

GnomAD4 genome

AF:

0.0000394

AC:

AN:

152230

Hom.:

Cov.:

AF XY:

0.0000269

AC XY:

AN XY:

74420

show subpopulations

Gnomad4 AFR

AF:

0.000120

Gnomad4 AMR

AF:

0.0000655

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:

0.0000231

Hom.:

Bravo

AF:

0.0000529

ESP6500AA

AF:

0.000911

AC:

ESP6500EA

AF:

0.00

AC:

ExAC

AF:

0.0000247

AC:

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

LINK: link

Submissions by phenotype

Inborn genetic diseases

Uncertain:1

Feb 26, 2025

Ambry Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The c.2326G>A (p.V776I) alteration is located in exon 10 (coding exon 10) of the TBC1D2B gene. This alteration results from a G to A substitution at nucleotide position 2326, causing the valine (V) at amino acid position 776 to be replaced by an isoleucine (I). Based on insufficient or conflicting evidence, the clinical significance of this alteration remains unclear. -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Benign

0.10

BayesDel_addAF

Benign

-0.22

BayesDel_noAF

Benign

-0.55

CADD

Benign

DANN

Uncertain

1.0

DEOGEN2

Benign

0.012

T;.

Eigen

Benign

0.10

Eigen_PC

Benign

0.14

FATHMM_MKL

Uncertain

0.92

LIST_S2

Uncertain

0.90

D;D

M_CAP

Benign

0.0066

MetaRNN

Benign

0.14

T;T

MetaSVM

Benign

-1.0

MutationAssessor

Benign

1.9

L;L

PrimateAI

Uncertain

0.64

PROVEAN

Benign

-0.79

N;N

REVEL

Benign

0.079

Sift

Benign

0.033

D;D

Sift4G

Uncertain

0.018

D;D

Polyphen

0.54

P;P

Vest4

0.19

MVP

0.51

MPC

0.32

ClinPred

0.52

GERP RS

4.8

RBP_binding_hub_radar

0.0

RBP_regulation_power_radar

1.1

Varity_R

0.17

gMVP

0.31

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