rs77499935

Variant names:

• chr5-74718812-A-G
• rs77499935
• NM_000521.4:c.1258A>G

Variant summary

Our verdict is Benign. The variant received -20 ACMG points: 0P and 20B. BP4_Strong BP6_Very_Strong BS1 BS2

The NM_000521.4(HEXB):​c.1258A>G​(p.Ile420Val) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00162 in 1,614,156 control chromosomes in the GnomAD database, including 42 homozygotes. In-silico tool predicts a benign outcome for this variant. 13/19 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Benign (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. I420T) has been classified as Uncertain significance.

• Frequency:
  • Genomes: 𝑓 0.0085 (21 hom., cov: 32)
  • Exomes 𝑓: 0.00090 (21 hom.)
• Consequence: HEXB NM_000521.4 missense
• Clinical Significance: Benign criteria provided, multiple submitters, no conflicts B:6
• Conservation: PhyloP100: 0.750
• Publications: 6 publications found

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, Genomics England PanelApp, Myriad Women’s Health, G2P, ClinGen

ACMG classification

Our verdict: Benign. The variant received -20 ACMG points.

• BP4: Computational evidence support a benign effect (MetaRNN=0.0046886504).
• BP6: Variant 5-74718812-A-G is Benign according to our data. Variant chr5-74718812-A-G is described in ClinVar as Benign. ClinVar VariationId is 256355.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.
• BS1: Variant frequency is greater than expected in population afr. GnomAd4 allele frequency = 0.00855 (1302/152314) while in subpopulation AFR AF = 0.0297 (1235/41568). AF 95% confidence interval is 0.0283. There are 21 homozygotes in GnomAd4. There are 616 alleles in the male GnomAd4 subpopulation. Median coverage is 32. This position passed quality control check.
• BS2: High Homozygotes in GnomAd4 at 21 AR gene

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_000521.4. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	HEXB	NM_000521.4	MANE Select	c.1258A>G	p.Ile420Val	missense	Exon 11 of 14	NP_000512.2	P07686
	HEXB	NM_001292004.2		c.583A>G	p.Ile195Val	missense	Exon 11 of 14	NP_001278933.1	Q5URX0

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	HEXB	ENST00000261416.12	TSL:1 MANE Select	c.1258A>G	p.Ile420Val	missense	Exon 11 of 14	ENSP00000261416.7	P07686
	HEXB	ENST00000511181.5	TSL:1	c.583A>G	p.Ile195Val	missense	Exon 11 of 14	ENSP00000426285.1	Q5URX0
	HEXB	ENST00000513336.5	TSL:3	c.193A>G	p.Ile65Val	missense	Exon 3 of 6	ENSP00000423713.1	H0Y9B6

Frequencies

GnomAD3 genomes AF: 0.00854 AC: 1300 AN: 152196 Hom.: 21 Cov.: 32

Gnomad AFR AF: 0.0297

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00334

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.000207

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.0000735

Gnomad OTH AF: 0.00479

GnomAD2 exomes AF: 0.00218 AC: 547 AN: 251412 AF XY: 0.00165

Gnomad AFR exome AF: 0.0300

Gnomad AMR exome AF: 0.00127

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.0000528

Gnomad OTH exome AF: 0.00130

GnomAD4 exome AF: 0.000900 AC: 1315 AN: 1461842 Hom.: 21 Cov.: 32 AF XY: 0.000762 AC XY: 554 AN XY: 727224

African (AFR) AF: 0.0323 AC: 1083 AN: 33480

American (AMR) AF: 0.00139 AC: 62 AN: 44724

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26132

East Asian (EAS) AF: 0.00 AC: 0 AN: 39694

South Asian (SAS) AF: 0.0000464 AC: 4 AN: 86254

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53420

Middle Eastern (MID) AF: 0.00260 AC: 15 AN: 5768

European-Non Finnish (NFE) AF: 0.0000423 AC: 47 AN: 1111978

Other (OTH) AF: 0.00172 AC: 104 AN: 60392

GnomAD4 genome AF: 0.00855 AC: 1302 AN: 152314 Hom.: 21 Cov.: 32 AF XY: 0.00827 AC XY: 616 AN XY: 74480

African (AFR) AF: 0.0297 AC: 1235 AN: 41568

American (AMR) AF: 0.00333 AC: 51 AN: 15300

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

East Asian (EAS) AF: 0.00 AC: 0 AN: 5172

South Asian (SAS) AF: 0.000207 AC: 1 AN: 4830

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10624

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

European-Non Finnish (NFE) AF: 0.0000735 AC: 5 AN: 68034

Other (OTH) AF: 0.00474 AC: 10 AN: 2110

Alfa AF: 0.00225 Hom.: 4

Bravo AF: 0.00932

ESP6500AA AF: 0.0266 AC: 117

ESP6500EA AF: 0.000116 AC: 1

ExAC AF: 0.00280 AC: 340

Asia WGS AF: 0.000866 AC: 3 AN: 3478

EpiCase AF: 0.00

EpiControl AF: 0.000119

ClinVar

ClinVar submissions as Germline

Significance: Benign

Revision: criteria provided, multiple submitters, no conflicts

Pathogenic	VUS	Benign	Condition
-	-	3	Sandhoff disease (3)
-	-	2	not specified (2)
-	-	1	not provided (1)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.059
BayesDel_addAF	Benign	-0.35	T
BayesDel_noAF	Benign	-0.25
CADD	Benign	1.5
DANN	Benign	0.74
DEOGEN2	Uncertain	0.48	T
Eigen	Benign	-0.60
Eigen_PC	Benign	-0.61
FATHMM_MKL	Benign	0.038	N
LIST_S2	Benign	0.83	T
MetaRNN	Benign	0.0047	T
MetaSVM	Benign	-1.1	T
PhyloP100		0.75
PrimateAI	Benign	0.24	T
PROVEAN	Benign	0.22	N
REVEL	Uncertain	0.33
Sift	Benign	1.0	T
Sift4G	Benign	1.0	T
Vest4		0.15
MVP		0.52
MPC		0.15
ClinPred		0.00084	T
GERP RS		-1.2
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
gMVP		0.55
Mutation Taster		=96/4	polymorphism

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: rs77499935; hg19: chr5-74014637;