6-3225797-C-T

Position:

• chr6-3225797-C-T

Variant summary

Our verdict is Likely pathogenic. Variant got 8 ACMG points: 8P and 0B. PM2 PP2 PP3_Strong PP5

The NM_178012.5(TUBB2B):​c.292G>A​(p.Gly98Arg) 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 Conflicting classifications of pathogenicity (no stars).

• Frequency:
  • Genomes: 𝑓 0.0 (0 hom., cov: 31)
  • Failed GnomAD Quality Control
• Consequence: TUBB2B NM_178012.5 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:3 U:1
• Conservation: PhyloP100: 7.78

Genes affected

TUBB2B (HGNC:30829): (tubulin beta 2B class IIb) The protein encoded by this gene is a beta isoform of tubulin, which binds GTP and is a major component of microtubules. This gene is highly similar to TUBB2A and TUBB2C. Defects in this gene are a cause of asymmetric polymicrogyria. [provided by RefSeq, Mar 2010]

ACMG classification

Verdict is Likely_pathogenic. Variant got 8 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), TUBB2B. . Gene score misZ 5.1195 (greater than the threshold 3.09). Trascript score misZ 6.9522 (greater than threshold 3.09). GenCC has associacion of gene with tubulinopathy-associated dysgyria, congenital fibrosis of extraocular muscles, cerebellar ataxia, intellectual disability, and dysequilibrium, complex cortical dysplasia with other brain malformations 7, complex cortical dysplasia with other brain malformations.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.991
• PP5: Variant 6-3225797-C-T is Pathogenic according to our data. Variant chr6-3225797-C-T is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 212497.We mark this variant Likely_pathogenic, oryginal submissions are: {Pathogenic=1, Likely_pathogenic=2, Uncertain_significance=1}.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
TUBB2B	NM_178012.5	c.292G>A	p.Gly98Arg	missense_variant	4/4	ENST00000259818.8

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
TUBB2B	ENST00000259818.8	c.292G>A	p.Gly98Arg	missense_variant	4/4	1	NM_178012.5	P1

Frequencies

GnomAD3 genomes AF: 0.00 AC: 0 AN: 151710 Hom.: 0 Cov.: 31 FAILED QC

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.00

Gnomad OTH AF: 0.00

GnomAD4 exome Cov.: 34

GnomAD4 genome Data not reliable, filtered out with message: AC0;AS_VQSR AF: 0.00 AC: 0 AN: 151710 Hom.: 0 Cov.: 31 AF XY: 0.00 AC XY: 0 AN XY: 74118

Gnomad4 AFR AF: 0.00

Gnomad4 AMR AF: 0.00

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.00

Gnomad4 OTH AF: 0.00

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:3 Uncertain:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

Complex cortical dysplasia with other brain malformations 7 Pathogenic:2

Likely pathogenic, criteria provided, single submitter	clinical testing	Genetic Services Laboratory, University of Chicago	Oct 29, 2013	- -
Likely pathogenic, criteria provided, single submitter	clinical testing	MGZ Medical Genetics Center	Nov 29, 2021	- -

not provided Pathogenic:1 Uncertain:1

Uncertain significance, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Dec 17, 2022	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 expected to disrupt TUBB2B protein function. ClinVar contains an entry for this variant (Variation ID: 212497). This missense change has been observed in individual(s) with cortical malformations (PMID: 23361065, 24860126). This variant is not present in population databases (gnomAD no frequency). This sequence change replaces glycine, which is neutral and non-polar, with arginine, which is basic and polar, at codon 98 of the TUBB2B protein (p.Gly98Arg). 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. -
Pathogenic, criteria provided, single submitter	clinical testing	GeneDx	Apr 04, 2023	The majority of missense variants in this gene are considered pathogenic (HGMD); 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: 23361065, 24860126, 25059107, 26934450) -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	1.0
BayesDel_addAF	Pathogenic	0.44	D
BayesDel_noAF	Pathogenic	0.39
CADD	Uncertain	25
DANN	Uncertain	0.99
DEOGEN2	Uncertain	0.54	D
Eigen	Pathogenic	0.70
Eigen_PC	Uncertain	0.51
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Pathogenic	0.98	D
M_CAP	Pathogenic	0.53	D
MetaRNN	Pathogenic	0.99	D
MetaSVM	Pathogenic	0.86	D
MutationAssessor	Pathogenic	4.6	H
MutationTaster	Benign	1.0	D
PrimateAI	Pathogenic	0.94	D
PROVEAN	Pathogenic	-4.6	D
REVEL	Pathogenic	0.84
Sift4G	Uncertain	0.033	D
Polyphen		0.93	P
Vest4		0.99
MutPred		0.92		Loss of ubiquitination at K103 (P = 0.0455);
MVP		0.82
ClinPred		1.0	D
GERP RS		5.2
Varity_R		0.83
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: rs797046075; hg19: chr6-3226031; COSMIC: COSV52534455;