rs1555162486

chr12-49186402-C-A

Variant summary

Our verdict is Pathogenic. Variant got 15 ACMG points: 15P and 0B. PM2 PM5 PP2 PP3_Moderate PP5_Very_Strong

The NM_006009.4(TUBA1A):c.283G>T(p.Gly95Cys) 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. 12/21 in silico tools predict a damaging outcome for this variant. Variant has been reported in ClinVar as Pathogenic (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. G95D) has been classified as Likely pathogenic.

• Frequency: Genomes: not found (cov: 30)
• Consequence: TUBA1A NM_006009.4 missense
• Clinical Significance: Pathogenic criteria provided, multiple submitters, no conflicts P:2
• Conservation: PhyloP100: 7.60

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 15 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr12-49186401-C-T is described in ClinVar as [Likely_pathogenic]. Clinvar id is 2578682.Status of the report is criteria_provided_single_submitter, 1 stars.
• PP2: Missense variant where missense usually causes diseases, TUBA1A
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.932
• PP5: Variant 12-49186402-C-A is Pathogenic according to our data. Variant chr12-49186402-C-A is described in ClinVar as [Pathogenic]. Clinvar id is 520585.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr12-49186402-C-A is described in Lovd as [Pathogenic]. Variant chr12-49186402-C-A is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
TUBA1A	NM_006009.4	c.283G>T	p.Gly95Cys	missense_variant	3/4	ENST00000301071.12
TUBA1A	NM_001270399.2	c.283G>T	p.Gly95Cys	missense_variant	3/4
TUBA1A	NM_001270400.2	c.178G>T	p.Gly60Cys	missense_variant	3/4

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
TUBA1A	ENST00000301071.12	c.283G>T	p.Gly95Cys	missense_variant	3/4	1	NM_006009.4	P1
TUBA1B-AS1	ENST00000656133.1	n.474-1881C>A		intron_variant, non_coding_transcript_variant

Frequencies

GnomAD3 genomes Cov.: 30

GnomAD4 exome Cov.: 48

GnomAD4 genome Cov.: 30

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Inborn genetic diseases Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Ambry Genetics

Oct 14, 2014

The c.283G>T (p.G95C) alteration is located in exon 3 (coding exon 3) of the TUBA1A gene. This alteration results from a G to T substitution at nucleotide position 283, causing the glycine (G) at amino acid position 95 to be replaced by a cysteine (C). The alteration is not observed in healthy cohorts:_x000D_ Based on data from the NHLBI Exome Sequencing Project (ESP), the TUBA1A c.283G>T alteration was not observed among 6,477 individuals tested. Allele frequency data for this nucleotide position are not currently available from the 1000 Genomes Project and the alteration is not currently listed in the Database of Single Nucleotide Polymorphisms (dbSNP). Though some variants may appear to be rare due to database-specific ethnic underrepresentation, rare missense alleles commonly exhibit a deleterious effect on protein function (Kryukov, 2007; Tennessen, 2012). IF USED, PULL THESE INTO REFERENCES:_x000D_ Kryukov GV, et al. (2007) Am J Hum Genet 80:727-739. Tennessen JA, et al. (2012) Science 337(64):64-69. The altered nucleotide is conserved throughout evolution:_x000D_ The c.283G nucleotide is completely conserved in available vertebrate species._x000D_ The altered amino acid is conserved throughout evolution:_x000D_ The p.G95 amino acid is completely conserved in available vertebrate species. The c.283G>T (p.G95C) alteration is located in coding exon 3 of the TUBA1A gene. The alteration consists of a G to T substitution at nucleotide position 283, causing the Glycine (G) at amino acid position 95 to be replaced by a Cysteine (C). The alteration is predicted deleterious by in silico models:_x000D_ The p.G95C alteration is predicted to be probably damaging by Polyphen and deleterious by SIFT in silico analyses._x000D_ The alteration is predicted not to affect splicing by in silico models:_x000D_ Based on BDGP and ESEfinder splice site in silico tools, this alteration does not have any significant effect on the native acceptor/donor splice site; however, direct evidence is unavailable Based on the available evidence, this alteration is classified as pathogenic. -

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.283G>T, p.(Gly95Cys) variant has been reported as a variant of de novo origin. This variant and associated phenotype was previously reported by Helbig et al. Genet Med, 2016 HPO-standardized clinical features were: Generalized tonic-clonic seizures (HP:0002069) -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.95
BayesDel_addAF	Pathogenic	0.42	D
BayesDel_noAF	Pathogenic	0.37
Cadd	Pathogenic	26
Dann	Uncertain	0.98
DEOGEN2	Uncertain	0.74	D;D;.;T;.
Eigen	Pathogenic	0.80
Eigen_PC	Pathogenic	0.76
FATHMM_MKL	Uncertain	0.96	D
M_CAP	Pathogenic	0.49	D
MetaRNN	Pathogenic	0.93	D;D;D;D;D
MetaSVM	Uncertain	0.63	D
MutationAssessor	Pathogenic	4.5	H;H;.;.;.
MutationTaster	Benign	1.0	D;D;D;D;D;D;D
PrimateAI	Pathogenic	0.87	D
PROVEAN	Pathogenic	-5.9	D;D;D;D;D
REVEL	Pathogenic	0.90
Sift	Pathogenic	0.0	D;D;.;.;.
Sift4G	Uncertain	0.027	D;D;D;.;D
Polyphen		1.0	D;D;.;.;.
Vest4		0.90
MutPred		0.76		Gain of catalytic residue at E90 (P = 0.0065);Gain of catalytic residue at E90 (P = 0.0065);.;.;.;
MVP		0.88
MPC		3.5
ClinPred		1.0	D
GERP RS		5.2
Varity_R		0.96
gMVP		0.99

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: rs1555162486; hg19: chr12-49580185;