Genetic Variant GLB1:p.Arg148Cys (chr3-33068245-G-A) – ACMG Classification: Pathogenic (23 pts)

Variant summary

Our verdict is Pathogenic. The variant received 23 ACMG points: 23P and 0B. PS3PM1PM2PM5PP2PP3_StrongPP5_Very_Strong

The NM_000404.4(GLB1):c.442C>T(p.Arg148Cys) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000713 in 1,613,856 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 Likely pathogenic (★★). ClinVar reports functional evidence for this variant: "SCV000915043: "COS-1 cells that transiently over-expressed the Arg148Cys GLB1 protein showed no residual Î²-galactosidase activity compared to cells that expressed the wildtype form (Caciotti et al. 2007)"" and additional evidence is available in ClinVar. Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R148L) has been classified as Likely pathogenic.

Frequency

Genomes: 𝑓 0.000033 ( 0 hom., cov: 32)

Exomes 𝑓: 0.000075 ( 0 hom. )

Consequence

GLB1
NM_000404.4 missense

Scores

Clinical Significance

Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:11O:1

Conservation

PhyloP100: 2.81

Publications

25 publications found

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 Gene-Disease associations (from GenCC):

GM1 gangliosidosis
Inheritance: AR Classification: DEFINITIVE Submitted by: ClinGen, Myriad Women’s Health
GM1 gangliosidosis type 3
Inheritance: AR Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: G2P, Labcorp Genetics (formerly Invitae), Genomics England PanelApp, Orphanet
mucopolysaccharidosis type 4B
Inheritance: AR Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: ClinGen, Labcorp Genetics (formerly Invitae), Orphanet, Genomics England PanelApp
GM1 gangliosidosis type 1
Inheritance: AR Classification: STRONG, SUPPORTIVE Submitted by: Genomics England PanelApp, Orphanet
GM1 gangliosidosis type 2
Inheritance: AR Classification: STRONG, SUPPORTIVE Submitted by: Genomics England PanelApp, Orphanet

GLB1 links:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Pathogenic. The variant received 23 ACMG points.

PS3

PS3 evidence extracted from ClinVar submissions: SCV000915043: "COS-1 cells that transiently over-expressed the Arg148Cys GLB1 protein showed no residual Î²-galactosidase activity compared to cells that expressed the wildtype form (Caciotti et al. 2007)"; SCV000958605: Experimental studies have shown that this missense change affects GLB1 function (PMID: 17221873).; SCV004100636: Experimental studies have shown that this missense change abrogates GLB1 enzymatic activity (Anna Caciotti et al 2007).

PM1

In a hotspot region, there are 7 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 3 uncertain in NM_000404.4

PM2

Very rare variant in population databases, with high coverage;

PM5

Other missense variant is known to change same aminoacid residue: Variant chr3-33068244-C-A is described in ClinVar as Likely_pathogenic. ClinVar VariationId is 2935679.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

PP2

Missense variant in the gene, where a lot of missense mutations are associated with disease in ClinVar. The gene has 110 curated pathogenic missense variants (we use a threshold of 10). The gene has 24 curated benign missense variants. Gene score misZ: 0.79419 (below the threshold of 3.09). Trascript score misZ: 1.1264 (below the threshold of 3.09). GenCC associations: The gene is linked to mucopolysaccharidosis type 4B, GM1 gangliosidosis, GM1 gangliosidosis type 3, GM1 gangliosidosis type 2, GM1 gangliosidosis type 1.

PP3

MetaRNN computational evidence supports a deleterious effect, 0.964

PP5

Variant 3-33068245-G-A is Pathogenic according to our data. Variant chr3-33068245-G-A is described in ClinVar as Pathogenic/Likely_pathogenic. ClinVar VariationId is 92907.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_000404.4. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein
GLB1	NM_000404.4	MANE Select	c.442C>T	p.Arg148Cys	missense	Exon 4 of 16	NP_000395.3
GLB1	NM_001317040.2		c.586C>T	p.Arg196Cys	missense	Exon 5 of 17	NP_001303969.2
GLB1	NM_001079811.3		c.352C>T	p.Arg118Cys	missense	Exon 4 of 16	NP_001073279.2

Ensembl Transcripts

Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
GLB1	ENST00000307363.10	TSL:1 MANE Select	c.442C>T	p.Arg148Cys	missense	Exon 4 of 16	ENSP00000306920.4	P16278
GLB1	ENST00000307377.12	TSL:1	c.246-2688C>T		intron	N/A	ENSP00000305920.8	E7EQ29
GLB1	ENST00000399402.7	TSL:2	c.352C>T	p.Arg118Cys	missense	Exon 4 of 16	ENSP00000382333.2	P16278

Frequencies

GnomAD3 genomes

AF:

0.0000329

AC:

AN:

152130

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:

0.0000588

Gnomad OTH

AF:

0.00

GnomAD2 exomes

AF:

0.0000401

AC:

AN:

249276

AF XY:

0.0000370

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.0000579

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.00

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.0000707

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.0000753

AC:

110

AN:

1461726

Hom.:

Cov.:

AF XY:

0.0000646

AC XY:

AN XY:

727156

show subpopulations

African (AFR)

AF:

0.0000299

AC:

AN:

33480

American (AMR)

AF:

0.0000447

AC:

AN:

44720

Ashkenazi Jewish (ASJ)

AF:

0.0000383

AC:

AN:

26132

East Asian (EAS)

AF:

0.00

AC:

AN:

39700

South Asian (SAS)

AF:

0.0000116

AC:

AN:

86250

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53380

Middle Eastern (MID)

AF:

0.000173

AC:

AN:

5764

European-Non Finnish (NFE)

AF:

0.0000854

AC:

AN:

1111922

Other (OTH)

AF:

0.000149

AC:

AN:

60378

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.460

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

AF:

0.0000329

AC:

AN:

152130

Hom.:

Cov.:

AF XY:

0.0000135

AC XY:

AN XY:

74312

show subpopulations

African (AFR)

AF:

0.0000241

AC:

AN:

41424

American (AMR)

AF:

0.00

AC:

AN:

15274

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3472

East Asian (EAS)

AF:

0.00

AC:

AN:

5188

South Asian (SAS)

AF:

0.00

AC:

AN:

4824

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10598

Middle Eastern (MID)

AF:

0.00

AC:

AN:

316

European-Non Finnish (NFE)

AF:

0.0000588

AC:

AN:

68030

Other (OTH)

AF:

0.00

AC:

AN:

2092

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.425

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Genome 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

Alfa

AF:

0.0000582

Hom.:

Bravo

AF:

0.0000604

ExAC

AF:

0.0000165

AC:

EpiCase

AF:

0.00

EpiControl

AF:

0.000119

ClinVar

ClinVar submissions

Significance:Pathogenic/Likely pathogenic

Revision:criteria provided, multiple submitters, no conflicts

View on ClinVar

Pathogenic

VUS

Benign

Condition

GM1 gangliosidosis (3)

Infantile GM1 gangliosidosis (4)

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

GM1 gangliosidosis;C0086652:Mucopolysaccharidosis, MPS-IV-B (1)

not provided (1)

Computational scores

Source: dbNSFP v4.9

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Pathogenic

0.65

BayesDel_addAF

Pathogenic

0.43

BayesDel_noAF

Pathogenic

0.56

CADD

Pathogenic

(source)

DANN

Pathogenic

1.0

DEOGEN2

Pathogenic

0.89

Eigen

Pathogenic

0.84

Eigen_PC

Pathogenic

0.70

FATHMM_MKL

Pathogenic

0.99

LIST_S2

Pathogenic

0.99

M_CAP

Pathogenic

0.74

MetaRNN

Pathogenic

0.96

MetaSVM

Pathogenic

0.98

PhyloP100

2.8

PrimateAI

Uncertain

0.66

PROVEAN

Pathogenic

-6.6

REVEL

Pathogenic

0.97

Sift

Pathogenic

0.0

Sift4G

Uncertain

0.020

Vest4

0.95

MVP

0.96

MPC

1.0

ClinPred

1.0

GERP RS

5.3

RBP_binding_hub_radar

0.0

RBP_regulation_power_radar

1.7

gMVP

0.99

Mutation Taster

=2/98

disease causing (ClinVar)

(source)

Splicing

Name

Calibrated prediction

Score

Prediction

Splicevardb

2.0

SpliceAI score (max)

0.070

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

Age Distribution

ClinVar

Computational scores

Splicing

Publications

Other links and lift over