rs951616685

Positions:

• chr5-74693693-G-C

Variant summary

Our verdict is Likely pathogenic. Variant got 6 ACMG points: 6P and 0B. PM2 PP3_Strong

The NM_000521.4(HEXB):​c.500G>C​(p.Gly167Ala) 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 Uncertain significance (★).

• Frequency: Genomes: not found (cov: 33)
• Consequence: HEXB NM_000521.4 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 6.94

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 (HGNC:):

ACMG classification

Verdict is Likely_pathogenic. Variant got 6 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.984

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
HEXB	NM_000521.4	c.500G>C	p.Gly167Ala	missense_variant	3/14	ENST00000261416.12	NP_000512.2
HEXB	NM_001292004.2	c.-176G>C		5_prime_UTR_variant	3/14		NP_001278933.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
HEXB	ENST00000261416.12	c.500G>C	p.Gly167Ala	missense_variant	3/14	1	NM_000521.4	ENSP00000261416.7
HEXB	ENST00000511181	c.-176G>C		5_prime_UTR_variant	3/14	1		ENSP00000426285.1
HEXB	ENST00000510820.1	n.219G>C		non_coding_transcript_exon_variant	1/4	3
HEXB	ENST00000513079.5	n.565G>C		non_coding_transcript_exon_variant	3/6	2

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 29

GnomAD4 genome Cov.: 33

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Sandhoff disease Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Apr 24, 2023

In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is expected to disrupt HEXB protein function. ClinVar contains an entry for this variant (Variation ID: 527970). This variant has not been reported in the literature in individuals affected with HEXB-related conditions. This variant is not present in population databases (gnomAD no frequency). This sequence change replaces glycine, which is neutral and non-polar, with alanine, which is neutral and non-polar, at codon 167 of the HEXB protein (p.Gly167Ala). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.75
BayesDel_addAF	Pathogenic	0.50	D
BayesDel_noAF	Pathogenic	0.48
CADD	Pathogenic	28
DANN	Uncertain	1.0
Eigen	Pathogenic	1.0
Eigen_PC	Pathogenic	0.92
FATHMM_MKL	Pathogenic	0.99	D
M_CAP	Pathogenic	0.32	D
MetaRNN	Pathogenic	0.98	D
MetaSVM	Pathogenic	1.1	D
PrimateAI	Benign	0.40	T
PROVEAN	Pathogenic	-5.8	D
REVEL	Pathogenic	0.90
Sift	Pathogenic	0.0	D
Sift4G	Pathogenic	0.0	D
Vest4		0.88
MutPred		0.91		Loss of catalytic residue at A168 (P = 0.1178);
MVP		0.98
MPC		0.73
ClinPred		1.0	D
GERP RS		5.8
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
gMVP		0.91

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: rs951616685; hg19: chr5-73989518;