20-59019556-TG-T

Position:

chr20-59019556-TG-T

Variant summary

Our verdict is Uncertain significance. Variant got 1 ACMG points: 5P and 4B. PVS1_StrongPP5BS2

The NM_030773.4(TUBB1):c.35delG(p.Cys12fs) variant causes a frameshift change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.0000378 in 1,614,102 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).

Frequency

Genomes: 𝑓 0.000053 ( 0 hom., cov: 33)

Exomes 𝑓: 0.000036 ( 0 hom. )

Consequence

TUBB1
NM_030773.4 frameshift

Scores

Not classified

Clinical Significance

Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:6U:3

Conservation

PhyloP100: 9.89

Variant links:

Genes affected

TUBB1 (HGNC:16257): (tubulin beta 1 class VI) This gene encodes a member of the beta tubulin protein family. Beta tubulins are one of two core protein families (alpha and beta tubulins) that heterodimerize and assemble to form microtubules. This protein is specifically expressed in platelets and megakaryocytes and may be involved in proplatelet production and platelet release. A mutations in this gene is associated with autosomal dominant macrothrombocytopenia. Two pseudogenes of this gene are found on chromosome Y.[provided by RefSeq, Jul 2010]

TUBB1 links:

Genome browser will be placed here

ACMG classification

Classification made for transcript

Verdict is Uncertain_significance. Variant got 1 ACMG points.

PVS1

Loss of function variant, product does not undergo nonsense mediated mRNA decay. Variant located near the start codon (<100nt), not predicted to undergo nonsense mediated mRNA decay. Fraction of 0.974 CDS is truncated, and there are 1 pathogenic variants in the truncated region.

PP5

Variant 20-59019556-TG-T is Pathogenic according to our data. Variant chr20-59019556-TG-T is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 586966.We mark this variant Likely_pathogenic, oryginal submissions are: {Uncertain_significance=3, Pathogenic=2, Likely_pathogenic=1}.

BS2

High AC in GnomAd4 at 8 AD gene.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
TUBB1	NM_030773.4 linkuse as main transcript	c.35delG	p.Cys12fs	frameshift_variant	1/4	ENST00000217133.2	NP_110400.1	Q9H4B7
TUBB1	XM_017028085.2 linkuse as main transcript	c.-10+3012delG		intron_variant			XP_016883574.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
TUBB1	ENST00000217133.2 linkuse as main transcript	c.35delG	p.Cys12fs	frameshift_variant	1/4	1	NM_030773.4	ENSP00000217133.1		Q9H4B7

Frequencies

GnomAD3 genomes

AF:

0.0000526

AC:

AN:

152216

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.00

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.0000654

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:

0.0000882

Gnomad OTH

AF:

0.000479

GnomAD3 exomes

AF:

0.0000318

AC:

AN:

251248

Hom.:

AF XY:

0.0000368

AC XY:

AN XY:

135822

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.0000578

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:

0.0000529

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.0000363

AC:

AN:

1461886

Hom.:

Cov.:

AF XY:

0.0000330

AC XY:

AN XY:

727240

show subpopulations

Gnomad4 AFR exome

AF:

0.00

Gnomad4 AMR exome

AF:

0.0000671

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:

0.0000441

Gnomad4 OTH exome

AF:

0.0000166

GnomAD4 genome

AF:

0.0000526

AC:

AN:

152216

Hom.:

Cov.:

AF XY:

0.0000807

AC XY:

AN XY:

74372

show subpopulations

Gnomad4 AFR

AF:

0.00

Gnomad4 AMR

AF:

0.0000654

Gnomad4 ASJ

AF:

0.00

Gnomad4 EAS

AF:

0.00

Gnomad4 SAS

AF:

0.00

Gnomad4 FIN

AF:

0.00

Gnomad4 NFE

AF:

0.0000882

Gnomad4 OTH

AF:

0.000479

Alfa

AF:

0.000142

Hom.:

Bravo

AF:

0.0000491

EpiCase

AF:

0.0000545

EpiControl

AF:

0.00

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:6Uncertain:3

Revision: criteria provided, conflicting classifications

LINK: link

Submissions by phenotype

Macrothrombocytopenia, isolated, 1, autosomal dominant

Pathogenic:4Uncertain:1

Pathogenic, no assertion criteria provided	research	Unidade de Genética Molecular, Centro Hospitalar Universitário do Porto	Jul 07, 2022	Variant identified in homozygosity in two of five affected members in the same family. PVS1, PP5, PP1 -
Pathogenic, criteria provided, single submitter	clinical testing	Women's Health and Genetics/Laboratory Corporation of America, LabCorp	Feb 14, 2024	Variant summary: TUBB1 c.35delG (p.Cys12LeufsX12) results in a premature termination codon, predicted to cause a truncation of the encoded protein or absence of the protein due to nonsense mediated decay, which are commonly known mechanisms for disease. The variant allele was found at a frequency of 3.2e-05 in 251248 control chromosomes (gnomAD). c.35delG has been reported in the literature in individuals affected with congenital hypothyroidism or inherited platelet disorders (Stoupa_2018, Bastida_2018). These data indicate that the variant may be associated with disease. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. The following publications have been ascertained in the context of this evaluation (PMID: 34662886, 28983057, 32757236, 30446499). ClinVar contains an entry for this variant (Variation ID: 586966). Based on the evidence outlined above, the variant was classified as pathogenic. -
Uncertain significance, criteria provided, single submitter	clinical testing	Mendelics	Apr 12, 2023	- -
Pathogenic, criteria provided, single submitter	clinical testing	ISTH-SSC Genomics in Thrombosis and Hemostasis, KU Leuven, Center for Molecular and Vascular Biology	-	- -
Pathogenic, no assertion criteria provided	literature only	OMIM	Oct 12, 2023	- -

not provided

Pathogenic:1Uncertain:1

Uncertain significance, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Oct 20, 2022	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. ClinVar contains an entry for this variant (Variation ID: 586966). This premature translational stop signal has been observed in individual(s) with thrombocytopenia and/or TUBB1-related macrothrombocytopenia (PMID: 28983057, 30446499, 32757236). This variant is present in population databases (rs773248042, gnomAD 0.006%). This sequence change creates a premature translational stop signal (p.Cys12Leufs*12) in the TUBB1 gene. It is expected to result in an absent or disrupted protein product. However, the current clinical and genetic evidence is not sufficient to establish whether loss-of-function variants in TUBB1 cause disease. -
Likely pathogenic, criteria provided, single submitter	clinical testing	GeneDx	Nov 14, 2024	Frameshift variant predicted to result in protein truncation or nonsense mediated decay in a gene for which loss-of-function is a known mechanism of disease; This variant is associated with the following publications: (PMID: 29333906, 30446499, 31589614, 34662886, 34516618, 32757236, 28983057, 37647632) -

Congenital hypothyroidism

Pathogenic:1

Pathogenic, no assertion criteria provided

research

Polak associated Lab, IMAGINE Institute

Oct 18, 2016

- -

TUBB1-related disorder

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

PreventionGenetics, part of Exact Sciences

Oct 06, 2022

The TUBB1 c.35delG variant is predicted to result in a frameshift and premature protein termination (p.Cys12Leufs*12). This variant has been reported in an individual with thyroid dysgenesis, and the variant was inherited from a parent with mild thyroid asymmetry but with normal thyroid function (Stoupa et al. 2018. PubMed ID: 30446499). This variant has also been reported in an individual with an inherited platelet disorder (Bastida et al. 2018. PubMed ID: 28983057) and an individual with nonsyndromic thrombocytopenia (Guéguen et al. 2020. PubMed ID: 32757236). This variant is reported in 0.0062% of alleles in individuals of European (Non-Finnish) descent in gnomAD (http://gnomad.broadinstitute.org/variant/20-57594611-TG-T). Although we suspect that this variant may be pathogenic, at this time, the clinical significance of this variant is uncertain due to the absence of conclusive functional and genetic evidence. -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

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

Below is the list of publications found by LitVar. It may be empty.

Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

LitVar

Other links and lift over