Genetic Variant TUBB2B:p.Thr399Met (chr6-3224893-G-A) – ACMG Classification: Uncertain_significance (5 pts)

Variant summary

Our verdict is Uncertain significance. Variant got 5 ACMG points: 5P and 0B. PM2PP2PP3_Moderate

The NM_178012.5(TUBB2B):c.1196C>T(p.Thr399Met) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000187 in 1,600,694 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★).

Frequency

Genomes: 𝑓 0.0000070 ( 0 hom., cov: 21)

Exomes 𝑓: 0.0000014 ( 0 hom. )

Consequence

TUBB2B
NM_178012.5 missense

Scores

Clinical Significance

Uncertain significance criteria provided, single submitter U:1

Conservation

PhyloP100: 9.60

Variant links:

Genes affected

TUBB2B (HGNC:30829): (tubulin beta 2B class IIb) The protein encoded by this gene is a beta isoform of tubulin, which binds GTP and is a major component of microtubules. This gene is highly similar to TUBB2A and TUBB2C. Defects in this gene are a cause of asymmetric polymicrogyria. [provided by RefSeq, Mar 2010]

TUBB2B links:

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ACMG classification

Classification made for transcript

Verdict is Uncertain_significance. Variant got 5 ACMG points.

PM2

Very rare variant in population databases, with high coverage;

PP2

Missense variant in the TUBB2B gene, where missense mutations are typically associated with disease (based on misZ statistic). The gene has 45 curated pathogenic missense variants (we use a threshold of 10). The gene has 2 curated benign missense variants. Gene score misZ: 5.1195 (above the threshold of 3.09). Trascript score misZ: 6.9522 (above the threshold of 3.09). GenCC associations: The gene is linked to tubulinopathy-associated dysgyria, congenital fibrosis of extraocular muscles, cerebellar ataxia, intellectual disability, and dysequilibrium, complex cortical dysplasia with other brain malformations 7, complex cortical dysplasia with other brain malformations.

PP3

MetaRNN computational evidence supports a deleterious effect, 0.877

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
TUBB2B	NM_178012.5 link	c.1196C>T	p.Thr399Met	missense_variant	Exon 4 of 4	ENST00000259818.8	NP_821080.1	Q9BVA1A0A384MEE3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
TUBB2B	ENST00000259818.8 link	c.1196C>T	p.Thr399Met	missense_variant	Exon 4 of 4	1	NM_178012.5	ENSP00000259818.6		Q9BVA1

Frequencies

GnomAD3 genomes

AF:

0.00000696

AC:

AN:

143754

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.00

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:

0.0000151

Gnomad OTH

AF:

0.00

GnomAD3 exomes

AF:

0.00000406

AC:

AN:

246536

Hom.:

AF XY:

0.00

AC XY:

AN XY:

133934

show subpopulations

Gnomad AFR exome

AF:

0.00

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:

0.00000901

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.00000137

AC:

AN:

1456940

Hom.:

Cov.:

AF XY:

0.00

AC XY:

AN XY:

724674

show subpopulations

Gnomad4 AFR exome

AF:

0.00

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:

0.00000180

Gnomad4 OTH exome

AF:

0.00

GnomAD4 genome

AF:

0.00000696

AC:

AN:

143754

Hom.:

Cov.:

AF XY:

0.0000144

AC XY:

AN XY:

69470

show subpopulations

Gnomad4 AFR

AF:

0.00

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:

0.0000151

Gnomad4 OTH

AF:

0.00

Bravo

AF:

0.00000378

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

LINK: link

Submissions by phenotype

Inborn genetic diseases

Uncertain:1

Jun 22, 2021

Ambry Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The c.1196C>T (p.T399M) alteration is located in exon 4 (coding exon 4) of the TUBB2B gene. This alteration results from a C to T substitution at nucleotide position 1196, causing the threonine (T) at amino acid position 399 to be replaced by a methionine (M). 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

Pathogenic

0.85

BayesDel_addAF

Pathogenic

0.18

BayesDel_noAF

Uncertain

0.030

CADD

Uncertain

DANN

Uncertain

1.0

DEOGEN2

Uncertain

0.46

Eigen

Pathogenic

0.88

Eigen_PC

Pathogenic

0.85

FATHMM_MKL

Pathogenic

1.0

LIST_S2

Uncertain

0.94

M_CAP

Pathogenic

0.64

MetaRNN

Pathogenic

0.88

MetaSVM

Uncertain

0.20

MutationAssessor

Pathogenic

3.4

PrimateAI

Pathogenic

0.91

PROVEAN

Uncertain

-2.9

REVEL

Pathogenic

0.66

Sift4G

Uncertain

0.014

Polyphen

0.99

Vest4

0.67

MutPred

0.53

Gain of catalytic residue at T399 (P = 0.034);

MVP

0.90

ClinPred

0.98

GERP RS

5.3

Varity_R

0.58

gMVP

0.87

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