19-6495445-C-T

Position:

• chr19-6495445-C-T

Variant summary

Our verdict is Uncertain significance. Variant got 4 ACMG points: 4P and 0B. PM2 PP2 PP3

The NM_006087.4(TUBB4A):​c.1054G>A​(p.Ala352Thr) 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 Uncertain significance (★).

• Frequency: Genomes: not found (cov: 32)
• Consequence: TUBB4A NM_006087.4 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1 O:1
• Conservation: PhyloP100: 7.76

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]

ACMG classification

Verdict is Uncertain_significance. Variant got 4 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP2: Missense variant in gene, where missense usually causes diseases (based on misZ statistic), TUBB4A. . Gene score misZ 4.2623 (greater than the threshold 3.09). Trascript score misZ 5.1229 (greater than threshold 3.09). GenCC has associacion of gene with torsion dystonia 4, TUBB4A-related neurologic disorder, hypomyelinating leukodystrophy 6.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.773

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
TUBB4A	NM_006087.4	c.1054G>A	p.Ala352Thr	missense_variant	4/4	ENST00000264071.7	NP_006078.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
TUBB4A	ENST00000264071.7	c.1054G>A	p.Ala352Thr	missense_variant	4/4	1	NM_006087.4	ENSP00000264071.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1 Other:1

Revision: criteria provided, single submitter

Submissions by phenotype

Hypomyelinating leukodystrophy 6 Uncertain:1 Other:1

Uncertain significance, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Jul 06, 2022	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. Algorithms developed to predict the effect of missense changes on protein structure and function are either unavailable or do not agree on the potential impact of this missense change (SIFT: "Deleterious"; PolyPhen-2: "Probably Damaging"; Align-GVGD: "Class C0"). ClinVar contains an entry for this variant (Variation ID: 267785). This missense change has been observed in individual(s) with clinical features of hypomyelinating leukodystrophy (PMID: 24785942). 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 352 of the TUBB4A protein (p.Ala352Thr). -
not provided, no classification provided	literature only	GeneReviews	-	- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.89
BayesDel_addAF	Uncertain	0.12	D
BayesDel_noAF	Uncertain	-0.070
CADD	Pathogenic	26
DANN	Benign	0.96
DEOGEN2	Benign	0.36	T
Eigen	Benign	0.071
Eigen_PC	Benign	0.14
FATHMM_MKL	Uncertain	0.96	D
LIST_S2	Uncertain	0.97	D
M_CAP	Pathogenic	0.87	D
MetaRNN	Pathogenic	0.77	D
MetaSVM	Uncertain	0.14	D
MutationAssessor	Uncertain	2.3	M
PrimateAI	Pathogenic	0.88	D
PROVEAN	Benign	-1.7	N
REVEL	Pathogenic	0.84
Sift4G	Uncertain	0.051	T
Polyphen		0.028	B
Vest4		0.88
MutPred		0.27		Loss of ubiquitination at K350 (P = 0.1601);
MVP		0.79
MPC		2.6
ClinPred		0.97	D
GERP RS		3.4
Varity_R		0.86
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: rs886041015; hg19: chr19-6495456;