19-6495931-G-A

Position:

• chr19-6495931-G-A

Variant summary

Our verdict is Likely pathogenic. Variant got 7 ACMG points: 7P and 0B. PM2 PP2 PP3_Moderate PP5_Moderate

The NM_006087.4(TUBB4A):​c.568C>T​(p.His190Tyr) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.000000684 in 1,461,894 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 Pathogenic (★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: TUBB4A NM_006087.4 missense
• Clinical Significance: Pathogenic criteria provided, single submitter P:2 O:1
• Conservation: PhyloP100: 9.79

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 Likely_pathogenic. Variant got 7 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, 0.911
• PP5: Variant 19-6495931-G-A is Pathogenic according to our data. Variant chr19-6495931-G-A is described in ClinVar as [Pathogenic]. Clinvar id is 192383.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
TUBB4A	NM_006087.4	c.568C>T	p.His190Tyr	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.568C>T	p.His190Tyr	missense_variant	4/4	1	NM_006087.4	ENSP00000264071	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD3 exomes AF: 0.00000398 AC: 1 AN: 251492 Hom.: 0 AF XY: 0.00 AC XY: 0 AN XY: 135920

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: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00000879

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461894 Hom.: 0 Cov.: 33 AF XY: 0.00 AC XY: 0 AN XY: 727248

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: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 8.99e-7

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

ExAC AF: 0.00000824 AC: 1

EpiCase AF: 0.00

EpiControl AF: 0.0000593

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:2 Other:1

Revision: criteria provided, single submitter

Submissions by phenotype

Hypomyelinating leukodystrophy 6 Pathogenic:2 Other:1

not provided, no classification provided	literature only	GeneReviews	-	- -
Pathogenic, no assertion criteria provided	literature only	OMIM	May 01, 2015	- -
Pathogenic, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Apr 09, 2023	For these reasons, this variant has been classified as Pathogenic. Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is not expected to disrupt TUBB4A protein function. ClinVar contains an entry for this variant (Variation ID: 192383). This missense change has been observed in individual(s) with TUBB4A-related conditions (PMID: 25772097, 27538619). In at least one individual the variant was observed to be de novo. It has also been observed to segregate with disease in related individuals. The frequency data for this variant in the population databases is considered unreliable, as metrics indicate poor data quality at this position in the gnomAD database. This sequence change replaces histidine, which is basic and polar, with tyrosine, which is neutral and polar, at codon 190 of the TUBB4A protein (p.His190Tyr). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.93
BayesDel_addAF	Pathogenic	0.20	D
BayesDel_noAF	Uncertain	0.050
CADD	Uncertain	24
DANN	Uncertain	0.99
DEOGEN2	Benign	0.30	T;.;.;T
Eigen	Pathogenic	0.94
Eigen_PC	Pathogenic	0.81
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Uncertain	0.92	D;D;D;D
M_CAP	Pathogenic	0.68	D
MetaRNN	Pathogenic	0.91	D;D;D;D
MetaSVM	Uncertain	0.57	D
MutationAssessor	Pathogenic	4.1	H;.;.;.
MutationTaster	Benign	1.0	D;D
PrimateAI	Uncertain	0.79	T
PROVEAN	Pathogenic	-4.8	D;.;.;.
REVEL	Pathogenic	0.78
Sift4G	Uncertain	0.029	D;D;.;.
Polyphen		1.0	D;.;.;.
Vest4		0.94
MutPred		0.66		Loss of catalytic residue at L192 (P = 0.1625);.;.;.;
MVP		0.90
MPC		2.9
ClinPred		0.99	D
GERP RS		4.0
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: rs761635539; hg19: chr19-6495942;