3-32996622-T-C

Variant names:

• chr3-32996622-T-C
• rs79603348
• NM_000404.4:c.*423A>G

Variant summary

Our verdict is Likely benign. The variant received -3 ACMG points: 0P and 3B. BP4_Moderate BS1_Supporting

The NM_000404.4(GLB1):​c.*423A>G variant causes a 3 prime UTR change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000889 in 254,086 control chromosomes in the GnomAD database, including 1 homozygotes. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency:
  • Genomes: 𝑓 0.0014 (1 hom., cov: 33)
  • Exomes 𝑓: 0.00015 (0 hom.)
• Consequence: GLB1 NM_000404.4 3_prime_UTR
• Clinical Significance: Uncertain significance criteria provided, single submitter U:2
• Conservation: PhyloP100: -0.0180
• Publications: 0 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: Likely_benign. The variant received -3 ACMG points.

• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.43).
• BS1: Variant frequency is greater than expected in population afr. GnomAd4 allele frequency = 0.00139 (211/152342) while in subpopulation AFR AF = 0.00491 (204/41580). AF 95% confidence interval is 0.00435. There are 1 homozygotes in GnomAd4. There are 104 alleles in the male GnomAd4 subpopulation. Median coverage is 33. This position passed quality control check. Existence of Clinvar submissions makes me limit the strength of this signal to Supporting

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
GLB1	NM_000404.4	c.*423A>G		3_prime_UTR_variant	Exon 16 of 16	ENST00000307363.10	NP_000395.3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
GLB1	ENST00000307363.10	c.*423A>G		3_prime_UTR_variant	Exon 16 of 16	1	NM_000404.4	ENSP00000306920.4
GLB1	ENST00000399402.7	c.*423A>G		3_prime_UTR_variant	Exon 16 of 16	2		ENSP00000382333.2
GLB1	ENST00000307377.12	c.*423A>G		downstream_gene_variant		1		ENSP00000305920.8

Frequencies

GnomAD3 genomes AF: 0.00139 AC: 211 AN: 152224 Hom.: 1 Cov.: 33

Gnomad AFR AF: 0.00492

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.000327

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: 0.00

Gnomad OTH AF: 0.000956

GnomAD4 exome AF: 0.000147 AC: 15 AN: 101744 Hom.: 0 Cov.: 0 AF XY: 0.000168 AC XY: 9 AN XY: 53508

African (AFR) AF: 0.00399 AC: 13 AN: 3256

American (AMR) AF: 0.00 AC: 0 AN: 4256

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 2466

East Asian (EAS) AF: 0.00 AC: 0 AN: 4926

South Asian (SAS) AF: 0.00 AC: 0 AN: 15122

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 4488

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 354

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 61718

Other (OTH) AF: 0.000388 AC: 2 AN: 5158

GnomAD4 genome AF: 0.00139 AC: 211 AN: 152342 Hom.: 1 Cov.: 33 AF XY: 0.00140 AC XY: 104 AN XY: 74492

African (AFR) AF: 0.00491 AC: 204 AN: 41580

American (AMR) AF: 0.000327 AC: 5 AN: 15292

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 3470

East Asian (EAS) AF: 0.00 AC: 0 AN: 5190

South Asian (SAS) AF: 0.00 AC: 0 AN: 4828

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10628

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 294

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 68034

Other (OTH) AF: 0.000946 AC: 2 AN: 2114

Alfa AF: 0.000791 Hom.: 0

Bravo AF: 0.00139

Asia WGS AF: 0.000289 AC: 1 AN: 3478

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, single submitter

Submissions by phenotype

Mucopolysaccharidosis, MPS-IV-B Uncertain:1

Jan 13, 2018

Illumina Laboratory Services, Illumina

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant was observed in the ICSL laboratory as part of a predisposition screen in an ostensibly healthy population. It had not been previously curated by ICSL or reported in the Human Gene Mutation Database (HGMD: prior to June 1st, 2018), and was therefore a candidate for classification through an automated scoring system. Utilizing variant allele frequency, disease prevalence and penetrance estimates, and inheritance mode, an automated score was calculated to assess if this variant is too frequent to cause the disease. Based on the score, this variant could not be ruled out of causing disease and therefore its association with disease required further investigation. A literature search was performed for the gene, cDNA change, and amino acid change (if applicable). No publications were found based on this search. This variant was therefore classified as a variant of unknown significance for this disease. -

GM1 gangliosidosis Uncertain:1

Jan 13, 2018

Illumina Laboratory Services, Illumina

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant was observed in the ICSL laboratory as part of a predisposition screen in an ostensibly healthy population. It had not been previously curated by ICSL or reported in the Human Gene Mutation Database (HGMD: prior to June 1st, 2018), and was therefore a candidate for classification through an automated scoring system. Utilizing variant allele frequency, disease prevalence and penetrance estimates, and inheritance mode, an automated score was calculated to assess if this variant is too frequent to cause the disease. Based on the score, this variant could not be ruled out of causing disease and therefore its association with disease required further investigation. A literature search was performed for the gene, cDNA change, and amino acid change (if applicable). No publications were found based on this search. This variant was therefore classified as a variant of unknown significance for this disease. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.43
CADD	Benign	10
DANN	Benign	0.89
PhyloP100		-0.018

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: rs79603348; hg19: chr3-33038114;