Genetic Variant TUBG1:p.Ser259* (chr17-42613931-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_001070.5(TUBG1):c.776C>A(p.Ser259*) variant causes a stop gained 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. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar. Synonymous variant affecting the same amino acid position (i.e. S259S) has been classified as Likely benign. Variant results in nonsense mediated mRNA decay.

Frequency

Genomes: not found (cov: 32)

Exomes 𝑓: 6.8e-7 ( 0 hom. )

Consequence

TUBG1
NM_001070.5 stop_gained

Scores

Clinical Significance

Not reported in ClinVar

Conservation

PhyloP100: 7.87

Publications

0 publications found

Variant links:

Genes affected

TUBG1 (HGNC:12417): (tubulin gamma 1) This gene encodes a member of the tubulin superfamily. The encoded protein localizes to the centrosome where it binds to microtubules as part of a complex referred to as the gamma-tubulin ring complex. The protein mediates microtubule nucleation and is required for microtubule formation and progression of the cell cycle. A pseudogene of this gene is found on chromosome 7. [provided by RefSeq, Jan 2009]

TUBG1 Gene-Disease associations (from GenCC):

lissencephaly spectrum disorders
Inheritance: AD Classification: DEFINITIVE Submitted by: ClinGen
complex cortical dysplasia with other brain malformations 4
Inheritance: AD Classification: STRONG, MODERATE Submitted by: Labcorp Genetics (formerly Invitae), Ambry Genetics

TUBG1 links:

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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;

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_001070.5. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	TUBG1	NM_001070.5	MANE Select	c.776C>A	p.Ser259*	stop_gained	Exon 8 of 11	NP_001061.2

Ensembl Transcripts

Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein
TUBG1	ENST00000251413.8	TSL:1 MANE Select	c.776C>A	p.Ser259*	stop_gained	Exon 8 of 11	ENSP00000251413.2
TUBG1	ENST00000681413.1		c.776C>A	p.Ser259*	stop_gained	Exon 8 of 11	ENSP00000505664.1
TUBG1	ENST00000951125.1		c.773C>A	p.Ser258*	stop_gained	Exon 8 of 11	ENSP00000621184.1

Frequencies

GnomAD3 genomes

Cov.:

GnomAD4 exome

AF:

6.84e-7

AC:

AN:

1461894

Hom.:

Cov.:

AF XY:

0.00

AC XY:

AN XY:

727248

show subpopulations

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

African (AFR)

AF:

0.0000299

AC:

AN:

33480

American (AMR)

AF:

0.00

AC:

AN:

44724

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26136

East Asian (EAS)

AF:

0.00

AC:

AN:

39700

South Asian (SAS)

AF:

0.00

AC:

AN:

86258

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53420

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5768

European-Non Finnish (NFE)

AF:

0.00

AC:

AN:

1112012

Other (OTH)

AF:

0.00

AC:

AN:

60396

⚠️ 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

Age Distribution

Exome Het

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

GnomAD4 genome

Cov.:

Alfa

AF:

0.00

Hom.:

Bravo

AF:

0.00000756

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.9

Name

Calibrated prediction

Score

Prediction

BayesDel_addAF

Pathogenic

0.62

BayesDel_noAF

Pathogenic

0.66

CADD

Pathogenic

(source)

DANN

Uncertain

0.99

Eigen

Pathogenic

0.72

Eigen_PC

Uncertain

0.52

FATHMM_MKL

Pathogenic

1.0

PhyloP100

7.9

Vest4

0.47

GERP RS

4.3

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

Variant Effect in Transcripts

RefSeq Transcripts

Ensembl Transcripts

Frequencies

Age Distribution

ClinVar

Computational scores

Splicing

Publications

Other links and lift over