chr5-74685199-G-A

Variant names:

• chr5-74685199-G-A
• rs1045177384
• ENST00000511181.5:c.-376-4129G>A

Variant summary

Our verdict is Likely benign. The variant received -2 ACMG points: 2P and 4B. PM2 BP4_Strong

The ENST00000513079.5(HEXB):​n.4G>A variant causes a non coding transcript exon change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000139 in 1,437,708 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency:
  • Genomes: 𝑓 0.000026 (0 hom., cov: 31)
  • Exomes 𝑓: 0.000012 (0 hom.)
• Consequence: HEXB ENST00000513079.5 non_coding_transcript_exon
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 0.445
• Publications: 0 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, G2P, ClinGen, Genomics England PanelApp, Myriad Women’s Health

ENSG00000306131 (HGNC:):

ACMG classification

Our verdict: Likely_benign. The variant received -2 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.78).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
HEXB	NM_001292004.2	c.-376-4129G>A		intron_variant	Intron 1 of 13		NP_001278933.1
HEXB	NM_000521.4	c.-62G>A		upstream_gene_variant		ENST00000261416.12	NP_000512.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
HEXB	ENST00000261416.12	c.-62G>A		upstream_gene_variant		1	NM_000521.4	ENSP00000261416.7

Frequencies

GnomAD3 genomes AF: 0.0000263 AC: 4 AN: 152164 Hom.: 0 Cov.: 31

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: 0.0000588

Gnomad OTH AF: 0.00

GnomAD4 exome AF: 0.0000124 AC: 16 AN: 1285544 Hom.: 0 Cov.: 28 AF XY: 0.0000143 AC XY: 9 AN XY: 629322

African (AFR) AF: 0.00 AC: 0 AN: 25580

American (AMR) AF: 0.00 AC: 0 AN: 22142

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 19546

East Asian (EAS) AF: 0.00 AC: 0 AN: 30680

South Asian (SAS) AF: 0.00 AC: 0 AN: 65226

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 31170

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 3698

European-Non Finnish (NFE) AF: 0.0000155 AC: 16 AN: 1033976

Other (OTH) AF: 0.00 AC: 0 AN: 53526

GnomAD4 genome AF: 0.0000263 AC: 4 AN: 152164 Hom.: 0 Cov.: 31 AF XY: 0.0000269 AC XY: 2 AN XY: 74328

African (AFR) AF: 0.00 AC: 0 AN: 41442

American (AMR) AF: 0.00 AC: 0 AN: 15292

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 3472

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

South Asian (SAS) AF: 0.00 AC: 0 AN: 4832

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10620

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 314

European-Non Finnish (NFE) AF: 0.0000588 AC: 4 AN: 68018

Other (OTH) AF: 0.00 AC: 0 AN: 2092

Alfa AF: 0.00 Hom.: 0

Bravo AF: 0.0000264

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Sandhoff disease Uncertain:1

Mar 23, 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	-0.78
CADD	Benign	7.2
DANN	Benign	0.81
PhyloP100		0.45
PromoterAI		0.089	Neutral
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.0

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: rs1045177384; hg19: chr5-73981024;