chr5-74696690-C-A

Variant names:

• chr5-74696690-C-A
• rs1376742145
• NM_000521.4:c.512-3C>A

Variant summary

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

The NM_000521.4(HEXB):​c.512-3C>A variant causes a splice region, intron change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000288 in 1,390,626 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 2/3 splice prediction tools predict no significant impact on normal splicing. Variant has been reported in ClinVar as Uncertain significance (no stars).

• Frequency:
  • Genomes: 𝑓 0.0000066 (0 hom., cov: 33)
  • Exomes 𝑓: 0.0000024 (0 hom.)
• Consequence: HEXB NM_000521.4 splice_region, intron
• Scores: Splicing: ADA: 0.5615
• Clinical Significance: Uncertain significance no assertion criteria provided U:1
• Conservation: PhyloP100: -0.844
• Publications: 1 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: 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=-0.66).

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.512-3C>A		splice_region intron	N/A	NP_000512.2	P07686
	HEXB	NM_001292004.2		c.-164-3C>A		splice_region intron	N/A	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.512-3C>A		splice_region intron	N/A	ENSP00000261416.7	P07686
	HEXB	ENST00000511181.5	TSL:1	c.-164-3C>A		splice_region intron	N/A	ENSP00000426285.1	Q5URX0
	HEXB	ENST00000510820.1	TSL:3	n.231-3C>A		splice_region intron	N/A

Frequencies

GnomAD3 genomes AF: 0.00000657 AC: 1 AN: 152156 Hom.: 0 Cov.: 33

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.000288

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.00

Gnomad OTH AF: 0.00

GnomAD4 exome AF: 0.00000242 AC: 3 AN: 1238470 Hom.: 0 Cov.: 20 AF XY: 0.00000159 AC XY: 1 AN XY: 627184

⚠️ The allele balance in gnomAD version 4 Exomes is significantly skewed from the expected value of 0.5.

African (AFR) AF: 0.00 AC: 0 AN: 29006

American (AMR) AF: 0.00 AC: 0 AN: 44108

Ashkenazi Jewish (ASJ) AF: 0.0000406 AC: 1 AN: 24602

East Asian (EAS) AF: 0.00 AC: 0 AN: 38368

South Asian (SAS) AF: 0.00 AC: 0 AN: 80914

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53070

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5320

European-Non Finnish (NFE) AF: 0.00000220 AC: 2 AN: 910334

Other (OTH) AF: 0.00 AC: 0 AN: 52748

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0.0183214), which strongly suggests a high chance of mosaicism in these individuals.

GnomAD4 genome AF: 0.00000657 AC: 1 AN: 152156 Hom.: 0 Cov.: 33 AF XY: 0.00 AC XY: 0 AN XY: 74322

African (AFR) AF: 0.00 AC: 0 AN: 41450

American (AMR) AF: 0.00 AC: 0 AN: 15278

Ashkenazi Jewish (ASJ) AF: 0.000288 AC: 1 AN: 3472

East Asian (EAS) AF: 0.00 AC: 0 AN: 5204

South Asian (SAS) AF: 0.00 AC: 0 AN: 4814

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10606

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 316

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 68012

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

Alfa AF: 0.00 Hom.: 0

ClinVar

ClinVar submissions as Germline

Significance: Uncertain significance

Revision: no assertion criteria provided

Pathogenic	VUS	Benign	Condition
-	1	-	Sandhoff disease (1)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.66
CADD	Benign	11
DANN	Benign	0.60
PhyloP100		-0.84
Mutation Taster		=17/83	disease causing

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Benign	0.56
dbscSNV1_RF	Benign	0.47
SpliceAI score (max)		0.34		Details are displayed if max score is > 0.2
DS_AL_spliceai		0.34		Position offset: 3

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

Other links and lift over

dbSNP: rs1376742145; hg19: chr5-73992515;