rs797046077

Positions:

• chr16-89935397-G-A

Variant summary

Our verdict is Uncertain significance. Variant got 3 ACMG points: 5P and 2B. PM1 PM2 PP2 BP4_Moderate

The NM_006086.4(TUBB3):​c.946G>A​(p.Val316Met) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000205 in 1,461,802 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 12/21 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★★).

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0000021 (0 hom.)
• Consequence: TUBB3 NM_006086.4 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: 1.63

Genes affected

TUBB3 (HGNC:20772): (tubulin beta 3 class III) This gene encodes a class III member of the beta tubulin protein family. Beta tubulins are one of two core protein families (alpha and beta tubulins) that heterodimerize and assemble to form microtubules. This protein is primarily expressed in neurons and may be involved in neurogenesis and axon guidance and maintenance. Mutations in this gene are the cause of congenital fibrosis of the extraocular muscles type 3. Alternate splicing results in multiple transcript variants. A pseudogene of this gene is found on chromosome 6. [provided by RefSeq, Oct 2010]

ACMG classification

Verdict is Uncertain_significance. Variant got 3 ACMG points.

• PM1: In a hotspot region, there are 5 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 6 uncertain in NM_006086.4
• PM2: Very rare variant in population databases, with high coverage
• PP2: Missense variant in gene, where missense usually causes diseases (based on misZ statistic), TUBB3. . Gene score misZ 4.5786 (greater than the threshold 3.09). Trascript score misZ 5.665 (greater than threshold 3.09). GenCC has associacion of gene with tubulinopathy-associated dysgyria, complex cortical dysplasia with other brain malformations 1, congenital fibrosis of extraocular muscles, fibrosis of extraocular muscles, congenital, 3A, with or without extraocular involvement.
• BP4: Computational evidence support a benign effect (MetaRNN=0.26385444).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
TUBB3	NM_006086.4	c.946G>A	p.Val316Met	missense_variant	4/4	ENST00000315491.12
TUBB3	NM_001197181.2	c.730G>A	p.Val244Met	missense_variant	4/4

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
TUBB3	ENST00000315491.12	c.946G>A	p.Val316Met	missense_variant	4/4	1	NM_006086.4	P1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome AF: 0.00000205 AC: 3 AN: 1461802 Hom.: 0 Cov.: 32 AF XY: 0.00000138 AC XY: 1 AN XY: 727210

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: 0.00000270

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 33

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not specified Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Genetic Services Laboratory, University of Chicago

Jun 05, 2015

- -

not provided Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Aug 02, 2022

This sequence change replaces valine, which is neutral and non-polar, with methionine, which is neutral and non-polar, at codon 316 of the TUBB3 protein (p.Val316Met). This variant is not present in population databases (gnomAD no frequency). This variant has not been reported in the literature in individuals affected with TUBB3-related conditions. ClinVar contains an entry for this variant (Variation ID: 212500). Algorithms developed to predict the effect of missense changes on protein structure and function (SIFT, PolyPhen-2, Align-GVGD) all suggest that this variant is likely to be tolerated. 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. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.23
BayesDel_addAF	Uncertain	0.017	T
BayesDel_noAF	Benign	-0.21
CADD	Benign	22
DANN	Benign	0.95
DEOGEN2	Benign	0.41	.;.;T
Eigen	Benign	-0.59
Eigen_PC	Benign	-0.40
FATHMM_MKL	Uncertain	0.90	D
LIST_S2	Uncertain	0.96	D;D;D
M_CAP	Uncertain	0.13	D
MetaRNN	Benign	0.26	T;T;T
MetaSVM	Benign	-0.89	T
MutationAssessor	Benign	-0.91	.;.;N
MutationTaster	Benign	0.98	D;D;D;D
PrimateAI	Uncertain	0.76	T
PROVEAN	Benign	-0.40	N;N;N
REVEL	Uncertain	0.31
Sift	Benign	0.18	T;.;.
Sift4G	Benign	0.31	T;T;T
Polyphen		0.0040	.;.;B
Vest4		0.35
MutPred		0.26		.;.;Loss of catalytic residue at V316 (P = 0.0473);
MVP		0.61
MPC		1.7
ClinPred		0.51	D
GERP RS		3.6
Varity_R		0.46
gMVP		0.93

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

Other links and lift over

dbSNP: rs797046077; hg19: chr16-90001805; COSMIC: COSV59248602; COSMIC: COSV59248602;