rs886041019

Variant names:

• chr19-6495337-T-C
• rs886041019
• NM_006087.4:c.1162A>G

Variant summary

Our verdict is Pathogenic. The variant received 18 ACMG points: 18P and 0B. PM1 PM2 PM5 PP3_Strong PP5_Very_Strong

The NM_006087.4(TUBB4A):​c.1162A>G​(p.Met388Val) 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. M388T) has been classified as Likely pathogenic.

• Frequency: Genomes: not found (cov: 32)
• Consequence: TUBB4A NM_006087.4 missense
• Clinical Significance: Likely pathogenic criteria provided, multiple submitters, no conflicts P:2 O:1
• Conservation: PhyloP100: 7.88
• Publications: 8 publications found

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 Gene-Disease associations (from GenCC):

• hypomyelinating leukodystrophy 6

  Inheritance: AD Classification: DEFINITIVE, STRONG, MODERATE, SUPPORTIVE Submitted by: Genomics England PanelApp, Labcorp Genetics (formerly Invitae), Orphanet, Illumina
• TUBB4A-related neurologic disorder

  Inheritance: AD Classification: DEFINITIVE, MODERATE Submitted by: Ambry Genetics, ClinGen
• torsion dystonia 4

  Inheritance: AD Classification: STRONG, SUPPORTIVE Submitted by: Genomics England PanelApp, Labcorp Genetics (formerly Invitae), Orphanet

ACMG classification

Our verdict: Pathogenic. The variant received 18 ACMG points.

• PM1: In a hotspot region, there are 4 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 4 uncertain in NM_006087.4
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr19-6495336-A-G is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 267791.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.955
• PP5: Variant 19-6495337-T-C is Pathogenic according to our data. Variant chr19-6495337-T-C is described in ClinVar as Likely_pathogenic. ClinVar VariationId is 267790.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
TUBB4A	NM_006087.4	c.1162A>G	p.Met388Val	missense_variant	Exon 4 of 4	ENST00000264071.7	NP_006078.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
TUBB4A	ENST00000264071.7	c.1162A>G	p.Met388Val	missense_variant	Exon 4 of 4	1	NM_006087.4	ENSP00000264071.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 32

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:2 Other:1

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not provided Pathogenic:2

Sep 20, 2019

Revvity Omics, Revvity

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Jan 23, 2017

GeneDx

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The M388V variant in the TUBB4A gene has been reported previously in association with hypomyelinating leukodystrophy with atrophy of the basal ganglia and cerebellum (Hamilton et al., 2014; Miyatake et al., 2014). The M388V variant was not observed in approximately 6,500 individuals of European and African American ancestry in the NHLBI Exome Sequencing Project, indicating it is not a common benign variant in these populations. The M388V variant is a conservative amino acid substitution, which occurs at a position that is conserved across species. In silico analysis is inconsistent in its predictions as to whether or not the variant is damaging to the protein structure/function. Missense variants in the same residue (M388I, M388T) have also been reported in association with hypomyelinating leukodystrophy with atrophy of the basal ganglia and cerebellum (Hamilton et al., 2014; Posey et al., 2016), supporting the functional importance of this region of the protein. The M388V variant is a strong candidate for a pathogenic variant. -

Hypomyelinating leukodystrophy 6 Other:1

-

GeneReviews

Significance: not provided

Review Status: no classification provided

Collection Method: literature only

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.98
BayesDel_addAF	Pathogenic	0.24	D
BayesDel_noAF	Uncertain	0.10
CADD	Pathogenic	26
DANN	Uncertain	0.98
DEOGEN2	Benign	0.11	T
Eigen	Pathogenic	0.83
Eigen_PC	Uncertain	0.65
FATHMM_MKL	Uncertain	0.94	D
LIST_S2	Benign	0.80	T
M_CAP	Pathogenic	0.92	D
MetaRNN	Pathogenic	0.95	D
MetaSVM	Pathogenic	0.90	D
MutationAssessor	Pathogenic	4.2	H
PhyloP100		7.9
PrimateAI	Pathogenic	0.84	D
PROVEAN	Benign	-2.1	N
REVEL	Pathogenic	0.95
Sift4G	Pathogenic	0.0010	D
Polyphen		1.0	D
Vest4		0.92
MutPred		0.80		Loss of MoRF binding (P = 0.0987);
MVP		0.92
MPC		1.5
ClinPred		1.0	D
GERP RS		3.4
Varity_R		0.95
gMVP		0.99
Mutation Taster		=24/76	disease causing (ClinVar)

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

Other links and lift over

dbSNP: rs886041019; hg19: chr19-6495348;