chr12-49186333-C-T

Position:

• chr12-49186333-C-T

Variant summary

Our verdict is Pathogenic. Variant got 16 ACMG points: 16P and 0B. PM1 PM2 PM5 PP2 PP3 PP5_Very_Strong

The NM_006009.4(TUBA1A):​c.352G>A​(p.Val118Met) variant causes a missense change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Likely pathogenic (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. V118L) has been classified as Likely pathogenic.

• Frequency: Genomes: not found (cov: 32)
• Consequence: TUBA1A NM_006009.4 missense
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:4
• Conservation: PhyloP100: 7.56

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 Pathogenic. Variant got 16 ACMG points.

• PM1: In a helix (size 12) in uniprot entity TBA1A_HUMAN there are 8 pathogenic changes around while only 0 benign (100%) in NM_006009.4
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr12-49186333-C-G is described in Lovd as [Likely_pathogenic].
• PP2: Missense variant in gene, where missense usually causes diseases (based on misZ statistic), TUBA1A. . Gene score misZ 5.584 (greater than the threshold 3.09). Trascript score misZ 8.7455 (greater than threshold 3.09). GenCC has associacion of gene with tubulinopathy-associated dysgyria, intellectual disability, autosomal dominant 40, tubulinopathy, lissencephaly due to TUBA1A mutation.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.837
• PP5: Variant 12-49186333-C-T is Pathogenic according to our data. Variant chr12-49186333-C-T is described in ClinVar as [Likely_pathogenic]. Clinvar id is 217023.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr12-49186333-C-T is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
TUBA1A	NM_006009.4	c.352G>A	p.Val118Met	missense_variant	3/4	ENST00000301071.12	NP_006000.2
TUBA1A	NM_001270399.2	c.352G>A	p.Val118Met	missense_variant	3/4		NP_001257328.1
TUBA1A	NM_001270400.2	c.247G>A	p.Val83Met	missense_variant	3/4		NP_001257329.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
TUBA1A	ENST00000301071.12	c.352G>A	p.Val118Met	missense_variant	3/4	1	NM_006009.4	ENSP00000301071	P1
TUBA1B-AS1	ENST00000656133.1	n.474-1950C>T		intron_variant, non_coding_transcript_variant

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 33

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:4

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Lissencephaly due to TUBA1A mutation Pathogenic:2

Pathogenic, criteria provided, single submitter	clinical testing	MGZ Medical Genetics Center	Sep 03, 2021	- -
Likely pathogenic, criteria provided, single submitter	clinical testing	UCLA Clinical Genomics Center, UCLA	May 20, 2014	- -

not provided Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

GeneDx

Mar 19, 2024

Not observed at significant frequency in large population cohorts (gnomAD); Missense variants in this gene are a common cause of disease and they are underrepresented in the general population; In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; This variant is associated with the following publications: (PMID: 25326637, 34356170, 30744660) -

Tubulinopathy Pathogenic:1

Pathogenic, criteria provided, single submitter

literature only

Institute of Human Genetics, FAU Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg

Jul 01, 2018

A variant that is classified as pathogenic has been identified in the TUBA1A gene in a born individual of unknown sex. The c.352G>A, p.(Val118Met) variant has been reported as a variant of de novo origin. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.80
BayesDel_addAF	Pathogenic	0.37	D
BayesDel_noAF	Pathogenic	0.30
CADD	Uncertain	24
DANN	Uncertain	1.0
DEOGEN2	Benign	0.31	T;T;.;T;.
Eigen	Pathogenic	0.91
Eigen_PC	Pathogenic	0.81
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Uncertain	0.88	.;D;D;D;D
M_CAP	Pathogenic	0.53	D
MetaRNN	Pathogenic	0.84	D;D;D;D;D
MetaSVM	Uncertain	0.57	D
MutationAssessor	Pathogenic	4.3	H;H;.;.;.
MutationTaster	Benign	1.0	D;D;D;D;D;D;D
PrimateAI	Pathogenic	0.88	D
PROVEAN	Benign	-1.6	N;N;N;N;D
REVEL	Uncertain	0.59
Sift	Pathogenic	0.0	D;D;.;.;.
Sift4G	Uncertain	0.0030	D;D;D;.;D
Polyphen		0.97	D;D;.;.;.
Vest4		0.47
MutPred		0.41		Gain of catalytic residue at L119 (P = 0.0072);Gain of catalytic residue at L119 (P = 0.0072);.;.;.;
MVP		0.92
MPC		3.3
ClinPred		1.0	D
GERP RS		5.2
Varity_R		0.80
gMVP		0.96

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: rs863224938; hg19: chr12-49580116;