Genetic Variant TUBB4A:p.Ala271Thr (chr19-6495688-C-T) – ACMG Classification: Likely_pathogenic (7 pts)

Variant summary

Our verdict is Likely pathogenic. Variant got 7 ACMG points: 7P and 0B. PM2PP2PP3_Strong

The NM_006087.4(TUBB4A):c.811G>A(p.Ala271Thr) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000205 in 1,461,724 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: not found (cov: 32)

Exomes 𝑓: 0.0000021 ( 0 hom. )

Consequence

TUBB4A
NM_006087.4 missense

Scores

Clinical Significance

Uncertain significance criteria provided, single submitter P:1U:1

Conservation

PhyloP100: 7.69

Variant links:

Genes affected

TUBB4A (HGNC:20774): (tubulin beta 4A class IVa) This gene encodes a member of the beta tubulin family. Beta tubulins are one of two core protein families (alpha and beta tubulins) that heterodimerize and assemble to form microtubules. Mutations in this gene cause hypomyelinating leukodystrophy-6 and autosomal dominant torsion dystonia-4. Alternate splicing results in multiple transcript variants encoding different isoforms. A pseudogene of this gene is found on chromosome X. [provided by RefSeq, Jan 2014]

TUBB4A links:

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ACMG classification

Classification made for transcript

Verdict is Likely_pathogenic. Variant got 7 ACMG points.

PM2

Very rare variant in population databases, with high coverage;

PP2

Missense variant in the TUBB4A gene, where missense mutations are typically associated with disease (based on misZ statistic). The gene has 39 curated pathogenic missense variants (we use a threshold of 10). The gene has 34 curated benign missense variants. Gene score misZ: 4.2623 (above the threshold of 3.09). Trascript score misZ: 5.1229 (above the threshold of 3.09). GenCC associations: The gene is linked to torsion dystonia 4, TUBB4A-related neurologic disorder, hypomyelinating leukodystrophy 6.

PP3

MetaRNN computational evidence supports a deleterious effect, 0.94

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
TUBB4A	NM_006087.4 link	c.811G>A	p.Ala271Thr	missense_variant	Exon 4 of 4	ENST00000264071.7	NP_006078.2	P04350

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
TUBB4A	ENST00000264071.7 link	c.811G>A	p.Ala271Thr	missense_variant	Exon 4 of 4	1	NM_006087.4	ENSP00000264071.1		P04350

Frequencies

GnomAD3 genomes

Cov.:

GnomAD3 exomes

AF:

0.00000399

AC:

AN:

250528

Hom.:

AF XY:

0.00

AC XY:

AN XY:

135624

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:

0.0000327

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.00

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.00000205

AC:

AN:

1461724

Hom.:

Cov.:

AF XY:

0.00000138

AC XY:

AN XY:

727194

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:

0.0000232

Gnomad4 FIN exome

AF:

0.00

Gnomad4 NFE exome

AF:

8.99e-7

Gnomad4 OTH exome

AF:

0.00

GnomAD4 genome

Cov.:

ExAC

AF:

0.00000824

AC:

ClinVar

Significance: Uncertain significance

Submissions summary: Pathogenic:1Uncertain:1

Revision: criteria provided, single submitter

LINK: link

Submissions by phenotype

Torsion dystonia 4

Pathogenic:1

Apr 01, 2013

OMIM

Significance: Pathogenic

Review Status: no assertion criteria provided

Collection Method: literature only

- -

not provided

Uncertain:1

Jun 20, 2024

GeneDx

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Reported in a patient with spasmodic dystonia, oromandibular dystonia, and dyskinesia in published literature (PMID: 23595291); Not observed at significant frequency in large population cohorts (gnomAD); 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: 30079973, 23595291, 35260199, 29127012) -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Uncertain

0.50

BayesDel_addAF

Pathogenic

0.37

BayesDel_noAF

Pathogenic

0.29

CADD

Pathogenic

DANN

Benign

0.93

DEOGEN2

Uncertain

0.61

Eigen

Uncertain

0.20

Eigen_PC

Benign

0.18

FATHMM_MKL

Pathogenic

0.97

LIST_S2

Uncertain

0.96

M_CAP

Pathogenic

0.91

MetaRNN

Pathogenic

0.94

MetaSVM

Uncertain

0.21

MutationAssessor

Pathogenic

4.0

PrimateAI

Uncertain

0.78

PROVEAN

Uncertain

-3.1

REVEL

Pathogenic

0.88

Sift4G

Uncertain

0.035

Polyphen

0.51

Vest4

0.83

MutPred

0.80

Loss of catalytic residue at A271 (P = 0.1055);

MVP

0.82

MPC

1.5

ClinPred

1.0

GERP RS

3.7

Varity_R

0.88

gMVP

0.98

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