rs1553610382

Variant names:

• chr3-33051950-TG-T
• rs1553610382
• NM_000404.4:c.846delC

Variant summary

Our verdict is Pathogenic. Variant got 18 ACMG points: 18P and 0B. PVS1 PM2 PP5_Very_Strong

The NM_000404.4(GLB1):​c.846delC​(p.Thr283GlnfsTer21) variant causes a frameshift change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. Variant has been reported in ClinVar as Pathogenic (★★). Variant results in nonsense mediated mRNA decay.

• Frequency: Genomes: not found (cov: 32)
• Consequence: GLB1 NM_000404.4 frameshift
• Clinical Significance: Pathogenic criteria provided, multiple submitters, no conflicts P:4
• Conservation: PhyloP100: -3.11

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 18 ACMG points.

• PVS1: Loss of function variant, product undergoes nonsense mediated mRNA decay. LoF is a known mechanism of disease.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 3-33051950-TG-T is Pathogenic according to our data. Variant chr3-33051950-TG-T is described in ClinVar as [Pathogenic]. Clinvar id is 557052.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.846delC	p.Thr283GlnfsTer21	frameshift_variant	Exon 8 of 16	ENST00000307363.10	NP_000395.3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
GLB1	ENST00000307363.10	c.846delC	p.Thr283GlnfsTer21	frameshift_variant	Exon 8 of 16	1	NM_000404.4	ENSP00000306920.4

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 34

GnomAD4 genome Cov.: 32

Bravo AF: 0.00000378

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:4

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

Mar 07, 2018

Counsyl

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

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

May 13, 2023

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change creates a premature translational stop signal (p.Thr283Glnfs*21) in the GLB1 gene. It is expected to result in an absent or disrupted protein product. Loss-of-function variants in GLB1 are known to be pathogenic (PMID: 18524657). This variant is not present in population databases (gnomAD no frequency). This premature translational stop signal has been observed in individual(s) with GM1-gangliosidosis (PMID: 17309651, 21214877). ClinVar contains an entry for this variant (Variation ID: 557052). For these reasons, this variant has been classified as Pathogenic. -

GM1 gangliosidosis Pathogenic:1

Apr 08, 2020

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

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Variant summary: GLB1 c.846delC (p.Thr283GlnfsX21) results in a premature termination codon, predicted to cause a truncation of the encoded protein or absence of the protein due to nonsense mediated decay, which are commonly known mechanisms for disease. Truncations downstream of this position have been classified as pathogenic by our laboratory. The variant was absent in 249510 control chromosomes (gnomAD). c.846delC has been reported in the literature in individuals affected with GM1 gangliosidosis (e.g. Coutinho_2012, Santamaria_2007). These data indicate that the variant is likely to be associated with disease. Two ClinVar submitters (evaluation after 2014) cite the variant as pathogenic. Based on the evidence outlined above, the variant was classified as pathogenic. -

GM1 gangliosidosis type 2 Pathogenic:1

May 28, 2019

Mendelics

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Computational scores

Source: dbNSFP v4.3

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

Other links and lift over

dbSNP: rs1553610382; hg19: chr3-33093442;