rs892920643

Variant names:

Variant summary

Our verdict is Pathogenic. The variant received 14 ACMG points: 14P and 0B. PM2PP3_StrongPP5_Very_Strong

The NM_000521.4(HEXB):c.558+5G>A variant causes a splice region, intron change. The variant allele was found at a frequency of 0.0000129 in 1,392,808 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 3/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Likely pathogenic (★★).

Frequency

Genomes: 𝑓 0.0000066 ( 0 hom., cov: 33)

Exomes 𝑓: 0.000014 ( 0 hom. )

Consequence

HEXB
NM_000521.4 splice_region, intron

Scores

Splicing: ADA: 1.000

Clinical Significance

Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:3U:1

Conservation

PhyloP100: 6.39

Publications

1 publications found

Variant links:

Genes affected

HEXB (HGNC:4879): (hexosaminidase subunit beta) Hexosaminidase B is the beta subunit of the lysosomal enzyme beta-hexosaminidase that, together with the cofactor GM2 activator protein, catalyzes the degradation of the ganglioside GM2, and other molecules containing terminal N-acetyl hexosamines. Beta-hexosaminidase is composed of two subunits, alpha and beta, which are encoded by separate genes. Both beta-hexosaminidase alpha and beta subunits are members of family 20 of glycosyl hydrolases. Mutations in the alpha or beta subunit genes lead to an accumulation of GM2 ganglioside in neurons and neurodegenerative disorders termed the GM2 gangliosidoses. Beta subunit gene mutations lead to Sandhoff disease (GM2-gangliosidosis type II). Alternatively spliced transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq, May 2014]

HEXB Gene-Disease associations (from GenCC):

Sandhoff disease
Inheritance: AR Classification: DEFINITIVE, STRONG Submitted by: Labcorp Genetics (formerly Invitae), Ambry Genetics, G2P, ClinGen, Genomics England PanelApp, Myriad Women’s Health

HEXB links:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Pathogenic. The variant received 14 ACMG points.

PM2

Very rare variant in population databases, with high coverage;

PP3

Splicing predictors support a deleterious effect. Scorers claiming Pathogenic: dbscSNV1_ADA, dbscSNV1_RF, max_spliceai. No scorers claiming Uncertain. No scorers claiming Benign.

PP5

Variant 5-74696744-G-A is Pathogenic according to our data. Variant chr5-74696744-G-A is described in ClinVar as Pathogenic/Likely_pathogenic. ClinVar VariationId is 554107.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
HEXB	NM_000521.4 link	c.558+5G>A		splice_region_variant, intron_variant	Intron 4 of 13	ENST00000261416.12	NP_000512.2	P07686A0A024RAJ6
HEXB	NM_001292004.2 link	c.-118+5G>A		splice_region_variant, intron_variant	Intron 4 of 13		NP_001278933.1	P07686Q5URX0

Ensembl

Gene	Transcript	HGVSc	Effect	Exon rank	TSL	MANE	Protein	UniProt
HEXB	ENST00000261416.12 link	c.558+5G>A	splice_region_variant, intron_variant	Intron 4 of 13	1	NM_000521.4	ENSP00000261416.7	P07686
HEXB	ENST00000511181.5 link	c.-118+5G>A	splice_region_variant, intron_variant	Intron 4 of 13	1		ENSP00000426285.1	Q5URX0
HEXB	ENST00000510820.1 link	n.277+5G>A	splice_region_variant, intron_variant	Intron 2 of 3	3
HEXB	ENST00000513079.5 link	n.623+5G>A	splice_region_variant, intron_variant	Intron 4 of 5	2

Frequencies

GnomAD3 genomes

AF:

0.00000657

AC:

AN:

152096

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.00

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:

0.0000147

Gnomad OTH

AF:

0.00

GnomAD2 exomes

AF:

0.00

AC:

AN:

244516

AF XY:

0.00

Gnomad AFR exome

AF:

0.00

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:

0.0000137

AC:

AN:

1240712

Hom.:

Cov.:

AF XY:

0.0000159

AC XY:

AN XY:

628298

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

29206

American (AMR)

AF:

0.00

AC:

AN:

44240

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

24632

East Asian (EAS)

AF:

0.00

AC:

AN:

38452

South Asian (SAS)

AF:

0.0000123

AC:

AN:

81134

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53046

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5324

European-Non Finnish (NFE)

AF:

0.0000175

AC:

AN:

911816

Other (OTH)

AF:

0.00

AC:

AN:

52862

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.463

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Exome Het

Variant carriers

<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:

0.00000657

AC:

AN:

152096

Hom.:

Cov.:

AF XY:

0.0000135

AC XY:

AN XY:

74306

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

41418

American (AMR)

AF:

0.00

AC:

AN:

15270

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3470

East Asian (EAS)

AF:

0.00

AC:

AN:

5198

South Asian (SAS)

AF:

0.00

AC:

AN:

4830

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10592

Middle Eastern (MID)

AF:

0.00

AC:

AN:

314

European-Non Finnish (NFE)

AF:

0.0000147

AC:

AN:

68006

Other (OTH)

AF:

0.00

AC:

AN:

2088

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.525

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Alfa

AF:

0.0000712

Hom.:

Bravo

AF:

0.0000227

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:3Uncertain:1

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

Sandhoff disease

Pathogenic:3Uncertain:1

Jul 07, 2022

Revvity Omics, Revvity

Significance:Likely pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Sep 21, 2023

Labcorp Genetics (formerly Invitae), Labcorp

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

For these reasons, this variant has been classified as Pathogenic. Variants that disrupt the consensus splice site are a relatively common cause of aberrant splicing (PMID: 17576681, 9536098). Studies have shown that this variant results in skipping of exon 4 and introduces a premature termination codon (PMID: 23046579). The resulting mRNA is expected to undergo nonsense-mediated decay. This sequence change falls in intron 4 of the HEXB gene. It does not directly change the encoded amino acid sequence of the HEXB protein. RNA analysis indicates that this variant induces altered splicing and may result in an absent or disrupted protein product. This variant is not present in population databases (gnomAD no frequency). This variant has been observed in individual(s) with Sandhoff disease (PMID: 23046579). In at least one individual the data is consistent with being in trans (on the opposite chromosome) from a pathogenic variant. ClinVar contains an entry for this variant (Variation ID: 554107). -

Sep 26, 2017

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. -

Apr 26, 2023

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: HEXB c.558+5G>A alters a conserved nucleotide located close to a canonical splice site and therefore could affect mRNA splicing, leading to a significantly altered protein sequence. Several computational tools predict a significant impact on normal splicing: Three predict the variant abolishes a 5' splicing donor site. At least one publication reports experimental evidence that this variant indeed affects mRNA splicing, resulting in the skipping of exon 4 which leads to a premature truncation (Gaignard_2013). The variant was absent in 244516 control chromosomes (gnomAD). c.558+5G>A has been reported in the literature in one individual affected with Sandhoff Disease, who had a pathogenic variant in trans (Gaignard_2013). These data do not allow for an unequivocal conclusion about variant significance. The following publication has been ascertained in the context of this evaluation (PMID: 23046579). Three clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar after 2014 and classified the variant as either pathogenic (n=1)/likely pathogenic (n=1) or VUS (n=1). Based on the evidence outlined above, the variant was classified as likely pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

BayesDel_noAF

Benign

-0.15

CADD

Benign

(source)

DANN

Benign

0.97

PhyloP100

6.4

Mutation Taster

=0/100

disease causing (ClinVar)

(source)

Splicing

Name

Calibrated prediction

Score

Prediction

dbscSNV1_ADA

Pathogenic

1.0

dbscSNV1_RF

Pathogenic

1.0

SpliceAI score (max)

0.99

Details are displayed if max score is > 0.2

DS_DL_spliceai

0.99

Position offset: -5

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

Publications

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Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

Publications

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

Age Distribution

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

Other links and lift over