dbSNP rs2234332: TUBA8:p.Tyr272* (chr22-18126794-C-A) – ACMG Classification: Uncertain_significance (2 pts)

Variant summary

Our verdict is Uncertain significance. The variant received 2 ACMG points: 2P and 0B. PM2

The NM_018943.3(TUBA8):c.816C>A(p.Tyr272*) variant causes a stop gained change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000000684 in 1,461,850 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar. Synonymous variant affecting the same amino acid position (i.e. Y272Y) has been classified as Likely benign. Variant results in nonsense mediated mRNA decay.

Frequency

Genomes: not found (cov: 31)

Exomes 𝑓: 6.8e-7 ( 0 hom. )

Consequence

TUBA8
NM_018943.3 stop_gained

Scores

Clinical Significance

Not reported in ClinVar

Conservation

PhyloP100: -1.79

Publications

3 publications found

Variant links:

Genes affected

TUBA8 (HGNC:12410): (tubulin alpha 8) This gene encodes a member of the alpha tubulin protein family. Alpha tubulins are one of two core protein families (alpha and beta tubulins) that heterodimerize and assemble to form microtubules. Mutations in this gene are associated with polymicrogyria and optic nerve hypoplasia. Alternate splicing results in multiple transcript variants. [provided by RefSeq, Jul 2010]

TUBA8 Gene-Disease associations (from GenCC):

polymicrogyria with optic nerve hypoplasia
Inheritance: Unknown, AR Classification: SUPPORTIVE, LIMITED, NO_KNOWN Submitted by: Labcorp Genetics (formerly Invitae), G2P, Orphanet, ClinGen

TUBA8 links:

ENSG00000288683 (HGNC:):

ENSG00000288683 links:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Uncertain_significance. The variant received 2 ACMG points.

PM2

Very rare variant in population databases, with high coverage;

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
TUBA8	NM_018943.3 link	c.816C>A	p.Tyr272*	stop_gained	Exon 4 of 5	ENST00000330423.8	NP_061816.1	Q9NY65-1
TUBA8	NM_001193414.2 link	c.618C>A	p.Tyr206*	stop_gained	Exon 4 of 5		NP_001180343.1	Q9NY65-2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	UniProt
TUBA8	ENST00000330423.8 link	c.816C>A	p.Tyr272*	stop_gained	Exon 4 of 5	1	NM_018943.3	ENSP00000333326.3	Q9NY65-1
ENSG00000288683	ENST00000474897.6 link	n.*706C>A		non_coding_transcript_exon_variant	Exon 8 of 9	5		ENSP00000434235.2	E9PRC5
ENSG00000288683	ENST00000474897.6 link	n.*706C>A		3_prime_UTR_variant	Exon 8 of 9	5		ENSP00000434235.2	E9PRC5

Frequencies

GnomAD3 genomes

Cov.:

GnomAD2 exomes

AF:

0.00000398

AC:

AN:

251384

AF XY:

0.00000736

show subpopulations

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 FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.00

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

6.84e-7

AC:

AN:

1461850

Hom.:

Cov.:

AF XY:

0.00000138

AC XY:

AN XY:

727224

show subpopulations

⚠️ The allele balance in gnomAD version 4 Exomes is significantly skewed from the expected value of 0.5.

African (AFR)

AF:

0.00

AC:

AN:

33480

American (AMR)

AF:

0.00

AC:

AN:

44724

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26128

East Asian (EAS)

AF:

0.00

AC:

AN:

39698

South Asian (SAS)

AF:

0.0000116

AC:

AN:

86256

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53418

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5768

European-Non Finnish (NFE)

AF:

0.00

AC:

AN:

1111984

Other (OTH)

AF:

0.00

AC:

AN:

60394

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0), which strongly suggests a high chance of mosaicism in these individuals.

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.375

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

GnomAD4 genome

Cov.:

ExAC

AF:

0.00000824

AC:

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

BayesDel_addAF

Pathogenic

0.40

BayesDel_noAF

Pathogenic

0.43

CADD

Pathogenic

(source)

DANN

Uncertain

0.99

Eigen

Benign

-0.16

Eigen_PC

Benign

-0.45

FATHMM_MKL

Benign

0.16

PhyloP100

-1.8

Vest4

0.49

GERP RS

-4.8

PromoterAI

-0.016

Neutral

(source)

Mutation Taster

=16/184

disease causing (fs/PTC)

(source)

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

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Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

Publications

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

ClinVar

Computational scores

Splicing

Publications

Other links and lift over