6-3225797-C-G

Variant names:

• chr6-3225797-C-G
• NM_178012.5:c.292G>C
• TUBB2B p.Gly98Arg

Variant summary

Our verdict is Likely pathogenic. The variant received 9 ACMG points: 9P and 0B. PS1_Moderate PM2 PP2 PP3_Strong

The NM_178012.5(TUBB2B):​c.292G>C​(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. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar. Another nucleotide change resulting in the same amino acid substitution has been previously reported as Likely pathogenic in ClinVar.

• Frequency: Genomes: not found (cov: 31)
• Consequence: TUBB2B NM_178012.5 missense
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 7.78
• Publications: 0 publications found

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]

TUBB2B Gene-Disease associations (from GenCC):

• complex cortical dysplasia with other brain malformations

  Inheritance: AD Classification: DEFINITIVE Submitted by: ClinGen
• complex cortical dysplasia with other brain malformations 7

  Inheritance: AD Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Orphanet, G2P, Labcorp Genetics (formerly Invitae)
• congenital fibrosis of extraocular muscles

  Inheritance: AD Classification: SUPPORTIVE, LIMITED Submitted by: Genomics England PanelApp, Orphanet
• tubulinopathy-associated dysgyria

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• cerebellar ataxia, intellectual disability, and dysequilibrium

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet

ACMG classification

Our verdict: Likely_pathogenic. The variant received 9 ACMG points.

• PS1: Transcript NM_178012.5 (TUBB2B) is affected with MISSENSE_VARIANT having same AA change as one Pathogenic present in ClinVar.
• PM2: Very rare variant in population databases, with high coverage
• PP2: Missense variant in the TUBB2B gene, where missense mutations are typically associated with disease (based on misZ statistic). The gene has 45 curated pathogenic missense variants (we use a threshold of 10). The gene has 2 curated benign missense variants. Gene score misZ: 5.1195 (above the threshold of 3.09). Trascript score misZ: 6.9522 (above the threshold of 3.09). GenCC associations: The gene is linked to congenital fibrosis of extraocular muscles, tubulinopathy-associated dysgyria, complex cortical dysplasia with other brain malformations 7, complex cortical dysplasia with other brain malformations, cerebellar ataxia, intellectual disability, and dysequilibrium.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.991

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_178012.5. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	TUBB2B	NM_178012.5	MANE Select	c.292G>C	p.Gly98Arg	missense	Exon 4 of 4	NP_821080.1	A0A384MEE3

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	TUBB2B	ENST00000259818.8	TSL:1 MANE Select	c.292G>C	p.Gly98Arg	missense	Exon 4 of 4	ENSP00000259818.6	Q9BVA1
	TUBB2B	ENST00000473006.1	TSL:3	n.409G>C		non_coding_transcript_exon	Exon 4 of 4
	TUBB2B	ENST00000680070.1		n.1222G>C		non_coding_transcript_exon	Exon 3 of 3

Frequencies

GnomAD3 genomes Cov.: 31

GnomAD4 exome Cov.: 34

GnomAD4 genome Cov.: 31

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	1.0
BayesDel_addAF	Pathogenic	0.44	D
BayesDel_noAF	Pathogenic	0.39
CADD	Uncertain	24
DANN	Uncertain	0.99
DEOGEN2	Uncertain	0.54	D
Eigen	Pathogenic	0.70
Eigen_PC	Uncertain	0.51
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Pathogenic	0.98	D
M_CAP	Pathogenic	0.50	D
MetaRNN	Pathogenic	0.99	D
MetaSVM	Pathogenic	0.86	D
MutationAssessor	Pathogenic	4.6	H
PhyloP100		7.8
PrimateAI	Pathogenic	0.94	D
PROVEAN	Pathogenic	-4.6	D
REVEL	Pathogenic	0.83
Sift4G	Uncertain	0.033	D
Varity_R		0.83
gMVP		0.99
Mutation Taster		=14/86	disease causing

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

MaxEntScan Visualizer can be used to analyze the impact of this mutation on the neighboring sequence.

Other links and lift over

hg19: chr6-3226031;