5-74689361-G-C

Variant names:

• chr5-74689361-G-C
• rs761117459
• NM_000521.4:c.333G>C

Variant summary

Our verdict is Uncertain significance. Variant got 1 ACMG points: 2P and 1B. PM2 BP4

The NM_000521.4(HEXB):​c.333G>C​(p.Trp111Cys) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000205 in 1,460,782 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 14/19 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0000021 (0 hom.)
• Consequence: HEXB NM_000521.4 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 0.721

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]

ACMG classification

Verdict is Uncertain_significance. Variant got 1 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.4201112).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
HEXB	NM_000521.4	c.333G>C	p.Trp111Cys	missense_variant	Exon 2 of 14	ENST00000261416.12	NP_000512.2
HEXB	NM_001292004.2	c.-343G>C		5_prime_UTR_variant	Exon 2 of 14		NP_001278933.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
HEXB	ENST00000261416.12	c.333G>C	p.Trp111Cys	missense_variant	Exon 2 of 14	1	NM_000521.4	ENSP00000261416.7
HEXB	ENST00000511181	c.-343G>C		5_prime_UTR_variant	Exon 2 of 14	1		ENSP00000426285.1
HEXB	ENST00000513079.5	n.398G>C		non_coding_transcript_exon_variant	Exon 2 of 6	2
HEXB	ENST00000515528.1	n.388G>C		non_coding_transcript_exon_variant	Exon 2 of 2	2

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD3 exomes AF: 0.0000119 AC: 3 AN: 251416 Hom.: 0 AF XY: 0.0000147 AC XY: 2 AN XY: 135868

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.0000867

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad SAS 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: 0.00000205 AC: 3 AN: 1460782 Hom.: 0 Cov.: 30 AF XY: 0.00000275 AC XY: 2 AN XY: 726704

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.0000671

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 33

Bravo AF: 0.00000378

ExAC AF: 0.00000824 AC: 1

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Sandhoff disease Uncertain:1

Jun 24, 2022

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces tryptophan, which is neutral and slightly polar, with cysteine, which is neutral and slightly polar, at codon 111 of the HEXB protein (p.Trp111Cys). This variant is present in population databases (rs761117459, gnomAD 0.009%). This variant has not been reported in the literature in individuals affected with HEXB-related conditions. Algorithms developed to predict the effect of missense changes on protein structure and function (SIFT, PolyPhen-2, Align-GVGD) all suggest that this variant is likely to be tolerated. 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. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.34
BayesDel_addAF	Benign	-0.13	T
BayesDel_noAF	Benign	-0.23
CADD	Benign	9.2
DANN	Benign	0.90
Eigen	Benign	-0.18
Eigen_PC	Benign	-0.43
FATHMM_MKL	Benign	0.10	N
M_CAP	Benign	0.061	D
MetaRNN	Benign	0.42	T
MetaSVM	Benign	-0.33	T
PrimateAI	Benign	0.25	T
PROVEAN	Uncertain	-4.3	D
REVEL	Benign	0.29
Sift	Benign	0.18	T
Sift4G	Benign	0.17	T
Vest4		0.24
MutPred		0.65		Gain of helix (P = 0.0199);
MVP		0.94
MPC		0.36
ClinPred		0.86	D
GERP RS		0.45
gMVP		0.65

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: rs761117459; hg19: chr5-73985186;