NM_000404.4:c.203G>A

Variant summary

Our verdict is Pathogenic. The variant received 17 ACMG points: 17P and 0B. PM1PM2PM5PP2PP3_ModeratePP5_Very_Strong

The NM_000404.4(GLB1):​c.203G>A​(p.Arg68Gln) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000744 in 1,613,946 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 (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R68L) has been classified as Likely pathogenic.

Frequency

Genomes: 𝑓 0.000026 ( 0 hom., cov: 32)
Exomes 𝑓: 0.0000055 ( 0 hom. )

Consequence

GLB1
NM_000404.4 missense

Scores

12
4
2

Clinical Significance

Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:4U:1

Conservation

PhyloP100: 7.91

Publications

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

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Pathogenic. The variant received 17 ACMG points.

PM1
In a helix (size 9) in uniprot entity BGAL_HUMAN there are 5 pathogenic changes around while only 0 benign (100%) 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 chr3-33072587-G-A is described in ClinVar as [Pathogenic]. Clinvar id is 944.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 2, GM1 gangliosidosis type 3, GM1 gangliosidosis type 1.
PP3
MetaRNN computational evidence supports a deleterious effect, 0.901
PP5
Variant 3-33072586-C-T is Pathogenic according to our data. Variant chr3-33072586-C-T is described in ClinVar as [Likely_pathogenic]. Clinvar id is 195074.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene Transcript HGVSc HGVSp Effect Exon rank MANE Protein UniProt
GLB1NM_000404.4 linkc.203G>A p.Arg68Gln missense_variant Exon 2 of 16 ENST00000307363.10 NP_000395.3 P16278

Ensembl

Gene Transcript HGVSc HGVSp Effect Exon rank TSL MANE Protein Appris UniProt
GLB1ENST00000307363.10 linkc.203G>A p.Arg68Gln missense_variant Exon 2 of 16 1 NM_000404.4 ENSP00000306920.4 P16278

Frequencies

GnomAD3 genomes
AF:
0.0000263
AC:
4
AN:
152184
Hom.:
0
Cov.:
32
show subpopulations
Gnomad AFR
AF:
0.0000483
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:
0.0000294
Gnomad OTH
AF:
0.00
GnomAD2 exomes
AF:
0.00000802
AC:
2
AN:
249456
AF XY:
0.0000148
show subpopulations
Gnomad AFR exome
AF:
0.000129
Gnomad AMR exome
AF:
0.00
Gnomad ASJ exome
AF:
0.00
Gnomad EAS exome
AF:
0.00
Gnomad FIN exome
AF:
0.00
Gnomad NFE exome
AF:
0.00
Gnomad OTH exome
AF:
0.00
GnomAD4 exome
AF:
0.00000547
AC:
8
AN:
1461644
Hom.:
0
Cov.:
31
AF XY:
0.00000688
AC XY:
5
AN XY:
727118
show subpopulations
African (AFR)
AF:
0.0000299
AC:
1
AN:
33470
American (AMR)
AF:
0.00
AC:
0
AN:
44722
Ashkenazi Jewish (ASJ)
AF:
0.00
AC:
0
AN:
26136
East Asian (EAS)
AF:
0.00
AC:
0
AN:
39700
South Asian (SAS)
AF:
0.0000348
AC:
3
AN:
86234
European-Finnish (FIN)
AF:
0.00
AC:
0
AN:
53420
Middle Eastern (MID)
AF:
0.00
AC:
0
AN:
5572
European-Non Finnish (NFE)
AF:
0.00000360
AC:
4
AN:
1112010
Other (OTH)
AF:
0.00
AC:
0
AN:
60380
Allele Balance Distribution
Red line indicates average allele balance
Average allele balance: 0.456
Heterozygous variant carriers
0
1
1
2
2
3
0.00
0.20
0.40
0.60
0.80
0.95
Allele balance

Age Distribution

Exome Het
Variant carriers
0
2
4
6
8
10
<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:
0.0000263
AC:
4
AN:
152302
Hom.:
0
Cov.:
32
AF XY:
0.0000269
AC XY:
2
AN XY:
74474
show subpopulations
African (AFR)
AF:
0.0000481
AC:
2
AN:
41558
American (AMR)
AF:
0.00
AC:
0
AN:
15302
Ashkenazi Jewish (ASJ)
AF:
0.00
AC:
0
AN:
3472
East Asian (EAS)
AF:
0.00
AC:
0
AN:
5180
South Asian (SAS)
AF:
0.00
AC:
0
AN:
4824
European-Finnish (FIN)
AF:
0.00
AC:
0
AN:
10616
Middle Eastern (MID)
AF:
0.00
AC:
0
AN:
294
European-Non Finnish (NFE)
AF:
0.0000294
AC:
2
AN:
68032
Other (OTH)
AF:
0.00
AC:
0
AN:
2112
Allele Balance Distribution
Red line indicates average allele balance
Average allele balance: 0.525
Heterozygous variant carriers
0
1
1
2
2
3
0.00
0.20
0.40
0.60
0.80
0.95
Allele balance
Alfa
AF:
0.0000173
Hom.:
0
Bravo
AF:
0.0000416
ExAC
AF:
0.0000165
AC:
2

ClinVar

Significance: Pathogenic/Likely pathogenic
Submissions summary: Pathogenic:4Uncertain:1
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:1Uncertain:1
Apr 10, 2018
Counsyl
Significance:Uncertain significance
Review Status:no assertion criteria provided
Collection Method:clinical testing

This submission and the accompanying classification are no longer maintained by the submitter. For more information on current observations and classification, please contact variantquestions@myriad.com. -

Jan 07, 2024
Fulgent Genetics, Fulgent Genetics
Significance:Likely pathogenic
Review Status:criteria provided, single submitter
Collection Method:clinical testing

- -

not provided Pathogenic:1
Feb 19, 2015
Eurofins Ntd Llc (ga)
Significance:Pathogenic
Review Status:criteria provided, single submitter
Collection Method:clinical testing

- -

GM1 gangliosidosis;C0086652:Mucopolysaccharidosis, MPS-IV-B Pathogenic:1
Nov 11, 2024
Labcorp Genetics (formerly Invitae), Labcorp
Significance:Pathogenic
Review Status:criteria provided, single submitter
Collection Method:clinical testing

This sequence change replaces arginine, which is basic and polar, with glutamine, which is neutral and polar, at codon 68 of the GLB1 protein (p.Arg68Gln). This variant is present in population databases (rs572237881, gnomAD 0.01%). This missense change has been observed in individual(s) with GM1 gangliosidosis (PMID: 19472408, 29439846). ClinVar contains an entry for this variant (Variation ID: 195074). Invitae Evidence Modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) indicates that this missense variant is expected to disrupt GLB1 protein function with a positive predictive value of 95%. Experimental studies have shown that this missense change affects GLB1 function (PMID: 19472408). This variant disrupts the p.Arg68 amino acid residue in GLB1. Other variant(s) that disrupt this residue have been determined to be pathogenic (PMID: 12644936, 25936995; internal data). This suggests that this residue is clinically significant, and that variants that disrupt this residue are likely to be disease-causing. For these reasons, this variant has been classified as Pathogenic. -

GM1 gangliosidosis Pathogenic:1
Jun 22, 2020
Women's Health and Genetics/Laboratory Corporation of America, LabCorp
Significance:Likely pathogenic
Review Status:criteria provided, single submitter
Collection Method:clinical testing

Variant summary: GLB1 c.203G>A (p.Arg68Gln) results in a conservative amino acid change located in the Glycoside hydrolase 35, catalytic domain of the encoded protein sequence. Four of five in-silico tools predict a damaging effect of the variant on protein function. The variant allele was found at a frequency of 8e-06 in 249456 control chromosomes. c.203G>A has been reported in the literature in at least one individual affected with GM1 Gangliosidosis (Hofer_2009). These data do not allow any conclusion about variant significance. At least one publication reports experimental evidence evaluating an impact on protein function. The most pronounced variant effect results in <10% of normal activity (Hofer_2009). Two clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar after 2014 without evidence for independent evaluation. One laboratory classified the variant as pathogenic, and one laboratory classified the variant as uncertain significance. In addition, p.R68W has been reported to associate with Gangliosidosis GM1 (HGMD database), indicating R68 is critical for GLB1 function. Based on the evidence outlined above, the variant was classified as likely pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name
Calibrated prediction
Score
Prediction
AlphaMissense
Benign
0.33
BayesDel_addAF
Pathogenic
0.41
D
BayesDel_noAF
Pathogenic
0.59
CADD
Pathogenic
33
DANN
Pathogenic
1.0
DEOGEN2
Pathogenic
0.81
.;.;.;.;D
Eigen
Pathogenic
1.0
Eigen_PC
Pathogenic
0.97
FATHMM_MKL
Pathogenic
0.98
D
LIST_S2
Pathogenic
1.0
.;.;D;D;D
M_CAP
Pathogenic
0.45
D
MetaRNN
Pathogenic
0.90
D;D;D;D;D
MetaSVM
Pathogenic
1.1
D
PhyloP100
7.9
PrimateAI
Uncertain
0.64
T
PROVEAN
Uncertain
-3.5
D;D;D;D;D
REVEL
Pathogenic
0.97
Sift
Uncertain
0.013
D;D;D;D;D
Sift4G
Uncertain
0.011
D;D;D;.;D
Polyphen
1.0
.;.;D;.;.
Vest4
0.98
MVP
0.99
MPC
0.93
ClinPred
1.0
D
GERP RS
5.8
RBP_binding_hub_radar
0.0
RBP_regulation_power_radar
1.8
gMVP
0.96
Mutation Taster
=1/99
disease causing (ClinVar)

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

Other links and lift over

dbSNP: rs572237881; hg19: chr3-33114078; COSMIC: COSV56565544; COSMIC: COSV56565544; API