chr3-33051989-A-G

Variant names:

• chr3-33051989-A-G
• rs376663785
• NM_000404.4:c.808T>C

Variant summary

Our verdict is Pathogenic. The variant received 11 ACMG points: 11P and 0B. PM1 PM2 PM5 PP2 PP3_Strong

The NM_000404.4(GLB1):​c.808T>C​(p.Tyr270His) variant causes a missense change involving the alteration of a conserved nucleotide. 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 not provided (no stars). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. Y270C) has been classified as Likely pathogenic.

• Frequency: Genomes: not found (cov: 32)
• Consequence: GLB1 NM_000404.4 missense
• Clinical Significance: not provided no classification provided O:1
• Conservation: PhyloP100: 8.93
• Publications: 16 publications found

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

ACMG classification

Our verdict: Pathogenic. The variant received 11 ACMG points.

• PM1: In a hotspot region, there are 8 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 5 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 chr3-33051988-T-C is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 198726.
• 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, 0.96

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
GLB1	NM_000404.4	c.808T>C	p.Tyr270His	missense_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.808T>C	p.Tyr270His	missense_variant	Exon 8 of 16	1	NM_000404.4	ENSP00000306920.4

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 34

GnomAD4 genome Cov.: 32

Alfa AF: 0.00 Hom.: 0

ClinVar

Significance: not provided

Submissions summary: Other:1

Revision: no classification provided

Submissions by phenotype

Infantile GM1 gangliosidosis Other:1

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GenomeConnect - GM1

Significance: not provided

Review Status: no classification provided

Collection Method: phenotyping only

Variant interpreted as Pathogenic and reported on 07-28-2020 by lab or GTR ID Federal State Budgetary Scientific Institution - Medical and Genetic Scientific Center (Moscow). GenomeConnect - GM1 assertions are reported exactly as they appear on the patient-provided report from the testing laboratory. Registry team members make no attempt to reinterpret the clinical significance of the variant. Phenotypic details are available under supporting information. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.85
BayesDel_addAF	Pathogenic	0.54	D
BayesDel_noAF	Pathogenic	0.54
CADD	Pathogenic	29
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.86	.;.;.;D
Eigen	Pathogenic	0.93
Eigen_PC	Pathogenic	0.86
FATHMM_MKL	Pathogenic	1.0	D
LIST_S2	Uncertain	0.95	.;.;D;D
M_CAP	Pathogenic	0.77	D
MetaRNN	Pathogenic	0.96	D;D;D;D
MetaSVM	Pathogenic	1.1	D
PhyloP100		8.9
PrimateAI	Uncertain	0.77	T
PROVEAN	Pathogenic	-4.8	D;D;D;D
REVEL	Pathogenic	0.97
Sift	Pathogenic	0.0	D;D;D;D
Sift4G	Pathogenic	0.0	D;D;D;D
Polyphen		1.0	.;.;D;.
Vest4		0.93
MutPred		0.83		Gain of glycosylation at Y270 (P = 0.0547);.;.;.;
MVP		0.98
MPC		0.99
ClinPred		1.0	D
GERP RS		5.3
gMVP		0.93
Mutation Taster		=3/97	disease causing

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

Other links and lift over

dbSNP: rs376663785; hg19: chr3-33093481;