3-33072543-C-T

Position:

chr3-33072543-C-T

Variant summary

Our verdict is Pathogenic. Variant got 18 ACMG points: 18P and 0B. PVS1PM2PP5_Very_Strong

The NM_000404.4(GLB1):c.245+1G>A variant causes a splice donor, intron change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000806 in 1,612,972 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. 3/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Pathogenic (★★).

Frequency

Genomes: 𝑓 0.000013 ( 0 hom., cov: 32)

Exomes 𝑓: 0.0000075 ( 0 hom. )

Consequence

GLB1
NM_000404.4 splice_donor, intron

Scores

Splicing: ADA: 1.000

Clinical Significance

Pathogenic criteria provided, multiple submitters, no conflicts P:6

Conservation

PhyloP100: 7.91

Variant links:

Genes affected

GLB1 (HGNC:4298): (galactosidase beta 1) This gene encodes a member of the glycosyl hydrolase 35 family of proteins. Alternative splicing results in multiple transcript variants, at least one of which encodes a preproprotein that is proteolytically processed to generate the mature lysosomal enzyme. This enzyme catalyzes the hydrolysis of a terminal beta-linked galactose residue from ganglioside substrates and other glycoconjugates. Mutations in this gene may result in GM1-gangliosidosis and Morquio B syndrome. [provided by RefSeq, Nov 2015]

GLB1 links:

GLB1 (HGNC:):

GLB1 links:

Genome browser will be placed here

ACMG classification

Classification made for transcript

Verdict is Pathogenic. Variant got 18 ACMG points.

PVS1

Splicing +-2 bp (donor or acceptor) variant, LoF is a know mechanism of disease, No cryptic splice site detected. Exon removal results in frameshift change.

PM2

Very rare variant in population databases, with high coverage;

PP5

Variant 3-33072543-C-T is Pathogenic according to our data. Variant chr3-33072543-C-T is described in ClinVar as [Pathogenic]. Clinvar id is 417873.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr3-33072543-C-T is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
GLB1	NM_000404.4 linkuse as main transcript	c.245+1G>A		splice_donor_variant, intron_variant		ENST00000307363.10	NP_000395.3	P16278

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
GLB1	ENST00000307363.10 linkuse as main transcript	c.245+1G>A		splice_donor_variant, intron_variant		1	NM_000404.4	ENSP00000306920.4		P16278

Frequencies

GnomAD3 genomes

AF:

0.0000131

AC:

AN:

152212

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.0000241

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:

0.0000147

Gnomad OTH

AF:

0.00

GnomAD3 exomes

AF:

0.00000802

AC:

AN:

249272

Hom.:

AF XY:

0.00000739

AC XY:

AN XY:

135242

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.00

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.0000556

Gnomad SAS exome

AF:

0.00

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.00000885

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.00000753

AC:

AN:

1460760

Hom.:

Cov.:

AF XY:

0.0000110

AC XY:

AN XY:

726694

show subpopulations

Gnomad4 AFR exome

AF:

0.0000299

Gnomad4 AMR exome

AF:

0.00

Gnomad4 ASJ exome

AF:

0.00

Gnomad4 EAS exome

AF:

0.0000504

Gnomad4 SAS exome

AF:

0.0000116

Gnomad4 FIN exome

AF:

0.00

Gnomad4 NFE exome

AF:

0.00000450

Gnomad4 OTH exome

AF:

0.0000166

GnomAD4 genome

AF:

0.0000131

AC:

AN:

152212

Hom.:

Cov.:

AF XY:

0.0000269

AC XY:

AN XY:

74360

show subpopulations

Gnomad4 AFR

AF:

0.0000241

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:

0.0000147

Gnomad4 OTH

AF:

0.00

Bravo

AF:

0.0000227

ExAC

AF:

0.00000827

AC:

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:6

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

Mucopolysaccharidosis, MPS-IV-B;C0268271:Infantile GM1 gangliosidosis;C0268272:GM1 gangliosidosis type 2;C0268273:GM1 gangliosidosis type 3

Pathogenic:3

Pathogenic, criteria provided, single submitter	clinical testing	Counsyl	Sep 06, 2017	- -
Likely pathogenic, no assertion criteria provided	research	Division of Human Genetics, Children's Hospital of Philadelphia	Dec 12, 2016	- -
Pathogenic, criteria provided, single submitter	clinical testing	Fulgent Genetics, Fulgent Genetics	Aug 10, 2021	- -

not provided

Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

GeneDx

Dec 10, 2023

Canonical splice site variant predicted to result in a null allele in a gene for which loss of function is a known mechanism of disease; Not observed at significant frequency in large population cohorts (gnomAD); This variant is associated with the following publications: (PMID: 25525159, 33737400, 15365997, 17221873, 18184943, 16941474) -

GM1 gangliosidosis;C0086652:Mucopolysaccharidosis, MPS-IV-B

Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Jan 26, 2024

This sequence change affects a donor splice site in intron 2 of the GLB1 gene. RNA analysis indicates that disruption of this splice site induces altered splicing and may result in an absent or disrupted protein product. This variant is present in population databases (rs778423653, gnomAD 0.005%). Disruption of this splice site has been observed in individuals with GM1-gangliosidosis (PMID: 15365997, 16941474, 17221873). ClinVar contains an entry for this variant (Variation ID: 417873). Studies have shown that disruption of this splice site results in skipping of exon 2 and introduces a premature termination codon (PMID: 17221873). The resulting mRNA is expected to undergo nonsense-mediated decay. For these reasons, this variant has been classified as Pathogenic. -

GM1 gangliosidosis

Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Women's Health and Genetics/Laboratory Corporation of America, LabCorp

Mar 30, 2020

Variant summary: GLB1 c.245+1G>A is located in a canonical splice-site and is predicted to affect mRNA splicing resulting in a significantly altered protein due to either exon skipping, shortening, or inclusion of intronic material. Several computational tools predict a significant impact on normal splicing: Four predict the variant abolishes a 5 splicing donor site. Experimental evidence supports these predictions demonstrating the variant gives rise to at least one aberrant transcript skipping exon 2 and leading to a premature termination codon (Caciotti_2007). The variant allele was found at a frequency of 8e-06 in 249272 control chromosomes (gnomAD). c.245+1G>A has been reported in the literature, in homozygous or compound heterozygous state, in multiple individuals affected with GM1 gangliosidosis (e.g. Caciotti_2007, Georgiou_2004, Hofer_2010, Santamaria_2006). These data indicate that the variant is very likely to be associated with disease. Testing of cells from homozygous patients revealed reduced (or absent) levels of both GLB1 and EBP mRNA expression and absent (0%) beta-Gal enzyme activity (e.g. Caciotti_2007, Hofer_2010). Three ClinVar submitters (evaluation after 2014) cite the variant as pathogenic/likely pathogenic. Based on the evidence outlined above, the variant was classified as pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

BayesDel_addAF

Pathogenic

0.51

BayesDel_noAF

Pathogenic

0.43

CADD

Pathogenic

DANN

Uncertain

1.0

Eigen

Pathogenic

1.2

Eigen_PC

Pathogenic

1.0

FATHMM_MKL

Pathogenic

0.99

GERP RS

5.2

Splicing

Name

Calibrated prediction

Score

Prediction

dbscSNV1_ADA

Pathogenic

1.0

dbscSNV1_RF

Pathogenic

0.93

SpliceAI score (max)

1.0

Details are displayed if max score is > 0.2

DS_DG_spliceai

0.32

Position offset: -3

DS_DL_spliceai

1.0

Position offset: 1

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