rs780523881

Variant names:

• chr3-33072643-C-G
• NM_000404.4:c.146G>C

Your query was ambiguous. Multiple possible variants found:

• chr3-33072643-C-G
• chr3-33072643-C-T

Variant summary

Our verdict is Pathogenic. Variant got 16 ACMG points: 16P and 0B. PM2 PM5 PP3_Strong PP5_Very_Strong

The NM_000404.4(GLB1):​c.146G>C​(p.Arg49Pro) variant causes a missense change. The variant was absent in control chromosomes in GnomAD project. 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. R49C) has been classified as Likely pathogenic.

• Frequency: Genomes: not found (cov: 32)
• Consequence: GLB1 NM_000404.4 missense
• Clinical Significance: Likely pathogenic criteria provided, multiple submitters, no conflicts P:2
• Conservation: PhyloP100: 6.17

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]

ACMG classification

Verdict is Pathogenic. Variant got 16 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chrnull-null-null-null is described in UniProt as null.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.973
• PP5: Variant 3-33072643-C-G is Pathogenic according to our data. Variant chr3-33072643-C-G is described in ClinVar as [Likely_pathogenic]. Clinvar id is 3251806.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
GLB1	NM_000404.4	c.146G>C	p.Arg49Pro	missense_variant	Exon 2 of 16	ENST00000307363.10	NP_000395.3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
GLB1	ENST00000307363.10	c.146G>C	p.Arg49Pro	missense_variant	Exon 2 of 16	1	NM_000404.4	ENSP00000306920.4

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 32

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Mucopolysaccharidosis, MPS-IV-B;C0268271:Infantile GM1 gangliosidosis;C0268272:GM1 gangliosidosis type 2;C0268273:GM1 gangliosidosis type 3 Pathogenic:1

May 13, 2024

Fulgent Genetics, Fulgent Genetics

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

GM1 gangliosidosis Pathogenic:1

Apr 22, 2024

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.146G>C (p.Arg49Pro) results in a non-conservative amino acid change located in the Glycoside hydrolase 35, catalytic domain (IPR031330) 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 249538 control chromosomes. To our knowledge, no occurrence of c.146G>C in individuals affected with GM1 Gangliosidosis and no experimental evidence demonstrating its impact on protein function have been reported. However, different variants affecting the same codon have been classified as pathogenic by our lab (c.145C>T, p.Arg49Cys) or as pathogenic in ClinVar (c.146G>A, p.Arg49His) supporting the critical relevance of codon 49 to GLB1 protein function. No submitters have cited clinical-significance assessments for this variant to ClinVar. 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	Pathogenic	0.82
BayesDel_addAF	Pathogenic	0.53	D
BayesDel_noAF	Pathogenic	0.52
CADD	Pathogenic	29
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.68	.;.;.;.;D
Eigen	Pathogenic	0.71
Eigen_PC	Pathogenic	0.68
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Pathogenic	0.98	.;.;D;D;D
M_CAP	Pathogenic	0.50	D
MetaRNN	Pathogenic	0.97	D;D;D;D;D
MetaSVM	Pathogenic	1.1	D
PrimateAI	Uncertain	0.53	T
PROVEAN	Pathogenic	-5.9	D;D;D;D;D
REVEL	Pathogenic	0.95
Sift	Uncertain	0.0010	D;D;D;D;D
Sift4G	Uncertain	0.0020	D;D;D;.;D
Polyphen		1.0	.;.;D;.;.
Vest4		0.96
MutPred		0.84		Loss of methylation at R49 (P = 0.022);.;Loss of methylation at R49 (P = 0.022);.;.;
MVP		0.99
MPC		1.1
ClinPred		1.0	D
GERP RS		5.0
gMVP		0.97

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.010		Details are displayed if max score is > 0.2

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

No publications associated with this variant yet.

Other links and lift over

hg19: chr3-33114135;