12-49185090-C-T

Variant summary

Our verdict is Uncertain significance. Variant got 5 ACMG points: 5P and 0B. PM1 PM2 PP2

The NM_006009.4(TUBA1A):c.1276G>A(p.Ala426Thr) variant causes a missense change. The variant was absent in control chromosomes in GnomAD project. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency: Genomes: not found (cov: 32)
• Consequence: TUBA1A NM_006009.4 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 4.68

Genes affected

TUBA1A (HGNC:20766): (tubulin alpha 1a) Microtubules of the eukaryotic cytoskeleton perform essential and diverse functions and are composed of a heterodimer of alpha and beta tubulins. The genes encoding these microtubule constituents belong to the tubulin superfamily, which is composed of six distinct families. Genes from the alpha, beta and gamma tubulin families are found in all eukaryotes. The alpha and beta tubulins represent the major components of microtubules, while gamma tubulin plays a critical role in the nucleation of microtubule assembly. There are multiple alpha and beta tubulin genes, which are highly conserved among species. This gene encodes alpha tubulin and is highly similar to the mouse and rat Tuba1 genes. Northern blot studies have shown that the gene expression is predominantly found in morphologically differentiated neurologic cells. This gene is one of three alpha-tubulin genes in a cluster on chromosome 12q. Mutations in this gene cause lissencephaly type 3 (LIS3) - a neurological condition characterized by microcephaly, intellectual disability, and early-onset epilepsy caused by defective neuronal migration. Alternative splicing results in multiple transcript variants encoding distinct isoforms. [provided by RefSeq, Jul 2017]

TUBA1B-AS1 (HGNC:56356): (TUBA1B antisense RNA 1)

ACMG classification

Verdict is Uncertain_significance. Variant got 5 ACMG points.

• PM1: In a hotspot region, there are 7 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 2 uncertain in NM_006009.4
• PM2: Very rare variant in population databases, with high coverage
• PP2: Missense variant where missense usually causes diseases, TUBA1A

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
TUBA1A	NM_006009.4	c.1276G>A	p.Ala426Thr	missense_variant	4/4	ENST00000301071.12
TUBA1A	NM_001270399.2	c.1276G>A	p.Ala426Thr	missense_variant	4/4
TUBA1A	NM_001270400.2	c.1171G>A	p.Ala391Thr	missense_variant	4/4

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
TUBA1A	ENST00000301071.12	c.1276G>A	p.Ala426Thr	missense_variant	4/4	1	NM_006009.4	P1
TUBA1B-AS1	ENST00000656133.1	n.474-3193C>T		intron_variant, non_coding_transcript_variant

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 30

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

not provided Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

May 12, 2022

This variant is not present in population databases (gnomAD no frequency). This sequence change replaces alanine, which is neutral and non-polar, with threonine, which is neutral and polar, at codon 426 of the TUBA1A protein (p.Ala426Thr). This variant has not been reported in the literature in individuals affected with TUBA1A-related conditions. 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 disruptive. 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	Pathogenic	0.99
BayesDel_addAF	Pathogenic	0.23	D
BayesDel_noAF	Uncertain	0.10
Cadd	Uncertain	24
Dann	Benign	0.94
DEOGEN2	Uncertain	0.49	T;T;.
Eigen	Uncertain	0.40
Eigen_PC	Uncertain	0.48
FATHMM_MKL	Uncertain	0.97	D
M_CAP	Pathogenic	0.61	D
MetaRNN	Uncertain	0.48	T;T;T
MetaSVM	Uncertain	0.42	D
MutationAssessor	Pathogenic	3.0	M;M;.
MutationTaster	Benign	1.0	D;D;D;D;D;D
PrimateAI	Uncertain	0.75	T
PROVEAN	Uncertain	-2.6	D;D;D
REVEL	Pathogenic	0.65
Sift	Pathogenic	0.0	D;D;.
Sift4G	Uncertain	0.038	D;D;D
Polyphen		0.17	B;B;.
Vest4		0.42
MutPred		0.41		Gain of phosphorylation at A426 (P = 0.0207);Gain of phosphorylation at A426 (P = 0.0207);.;
MVP		0.80
MPC		3.0
ClinPred		0.99	D
GERP RS		5.5
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.81
gMVP		0.91

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

No publications associated with this variant yet.

Other links and lift over

hg19: chr12-49578873;