Genetic Variant GLB1:p.Tyr485Cys (chr3-33016734-T-C) – ACMG Classification: Uncertain_significance (5 pts)

Variant summary

Our verdict is Uncertain significance. Variant got 5 ACMG points: 5P and 0B. PM2PP3_ModeratePP5

The NM_000404.4(GLB1):c.1454A>G(p.Tyr485Cys) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000124 in 1,614,016 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).

Frequency

Genomes: 𝑓 0.0000066 ( 0 hom., cov: 32)

Exomes 𝑓: 6.8e-7 ( 0 hom. )

Consequence

GLB1
NM_000404.4 missense

Scores

Clinical Significance

Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:1U:2

Conservation

PhyloP100: 0.217

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:

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ACMG classification

Classification made for transcript

Verdict is Uncertain_significance. Variant got 5 ACMG points.

PM2

Very rare variant in population databases, with high coverage;

PP3

MetaRNN computational evidence supports a deleterious effect, 0.921

PP5

Variant 3-33016734-T-C is Pathogenic according to our data. Variant chr3-33016734-T-C is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 555363.We mark this variant Likely_pathogenic, oryginal submissions are: {Uncertain_significance=2, Pathogenic=1}.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
GLB1	NM_000404.4 link	c.1454A>G	p.Tyr485Cys	missense_variant	Exon 14 of 16	ENST00000307363.10	NP_000395.3	P16278

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
GLB1	ENST00000307363.10 link	c.1454A>G	p.Tyr485Cys	missense_variant	Exon 14 of 16	1	NM_000404.4	ENSP00000306920.4		P16278

Frequencies

GnomAD3 genomes

AF:

0.00000657

AC:

AN:

152220

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.00

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.0000655

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:

0.00

Gnomad OTH

AF:

0.00

GnomAD4 exome

AF:

6.84e-7

AC:

AN:

1461796

Hom.:

Cov.:

AF XY:

0.00

AC XY:

AN XY:

727200

show subpopulations

Gnomad4 AFR exome

AF:

0.00

Gnomad4 AMR exome

AF:

0.00

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:

0.00

Gnomad4 OTH exome

AF:

0.0000166

GnomAD4 genome

AF:

0.00000657

AC:

AN:

152220

Hom.:

Cov.:

AF XY:

0.00

AC XY:

AN XY:

74368

show subpopulations

Gnomad4 AFR

AF:

0.00

Gnomad4 AMR

AF:

0.0000655

Gnomad4 ASJ

AF:

0.00

Gnomad4 EAS

AF:

0.00

Gnomad4 SAS

AF:

0.00

Gnomad4 FIN

AF:

0.00

Gnomad4 NFE

AF:

0.00

Gnomad4 OTH

AF:

0.00

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:1Uncertain:2

Revision: criteria provided, conflicting classifications

LINK: link

Submissions by phenotype

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

Pathogenic:1

Dec 07, 2023

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces tyrosine, which is neutral and polar, with cysteine, which is neutral and slightly polar, at codon 485 of the GLB1 protein (p.Tyr485Cys). This variant is not present in population databases (gnomAD no frequency). This missense change has been observed in individual(s) with Morquio B disease (PMID: 23151865). In at least one individual the data is consistent with being in trans (on the opposite chromosome) from a pathogenic variant. ClinVar contains an entry for this variant (Variation ID: 555363). Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is expected to disrupt GLB1 protein function with a positive predictive value of 95%. For these reasons, this variant has been classified as Pathogenic. -

not specified

Uncertain:1

Sep 24, 2024

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

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Variant summary: GLB1 c.1454A>G (p.Tyr485Cys) results in a non-conservative amino acid change located in the Beta-galactosidase 1-like , first all-beta domain (IPR048912) of the encoded protein sequence. Five of five in-silico tools predict a damaging effect of the variant on protein function. The variant was absent in 249586 control chromosomes. The available data on variant occurrences in the general population are insufficient to allow any conclusion about variant significance. c.1454A>G has been reported in the literature in at-least one individual affected with Mucopolysaccharidosis Type IVB (Morquio Syndrome B) (Lei_2012). These data do not allow any conclusion about variant significance. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported.The following publication has been ascertained in the context of this evaluation (PMID: 23151865). ClinVar contains an entry for this variant (Variation ID: 555363). Based on the evidence outlined above, the variant was classified as uncertain significance. -

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

Uncertain:1

Dec 07, 2017

Counsyl

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Uncertain

0.40

BayesDel_addAF

Pathogenic

0.48

BayesDel_noAF

Pathogenic

0.46

CADD

Uncertain

DANN

Uncertain

1.0

Eigen

Uncertain

0.20

Eigen_PC

Benign

0.048

FATHMM_MKL

Benign

0.51

LIST_S2

Pathogenic

0.98

.;.;D

M_CAP

Pathogenic

0.62

MetaRNN

Pathogenic

0.92

D;D;D

MetaSVM

Pathogenic

0.97

PrimateAI

Uncertain

0.59

PROVEAN

Pathogenic

-6.7

D;D;D

REVEL

Pathogenic

0.79

Sift

Uncertain

0.0010

D;D;D

Sift4G

Pathogenic

0.0010

D;D;D

Polyphen

1.0

.;.;D

Vest4

0.73

MutPred

0.66

Loss of sheet (P = 0.0315);.;.;

MVP

0.98

MPC

0.96

ClinPred

0.98

GERP RS

3.4

gMVP

0.94

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