Genetic Variant HEXA:p.Arg499His (chr15-72345476-C-T) – ACMG Classification: Pathogenic (20 pts)

Variant summary

Our verdict is Pathogenic. The variant received 20 ACMG points: 20P and 0B. PS3PM1PM5PP3_StrongPP5_Very_Strong

The NM_000520.6(HEXA):c.1496G>A(p.Arg499His) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.0000682 in 1,614,084 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Pathogenic (★★). ClinVar reports functional evidence for this variant: "SCV000263008: "Biosynthetic studies of the R499H alteration revealed the synthesis of an abnormal a-subunit which did not associate with the b-subunit. It was not processed into the mature lysosomal form and appeared to be retained and degraded in the endoplasmic reticulum, possibly due to misfolding. However some residual enzyme activity (~3%) was observed (Paw, 1990)."" and additional evidence is available in ClinVar. Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R499C) has been classified as Pathogenic.

Frequency

Genomes: 𝑓 0.000033 ( 0 hom., cov: 34)

Exomes 𝑓: 0.000072 ( 0 hom. )

Consequence

HEXA
NM_000520.6 missense

Scores

Clinical Significance

Pathogenic criteria provided, multiple submitters, no conflicts P:18

Conservation

PhyloP100: 7.56

Publications

19 publications found

Variant links:

Genes affected

HEXA (HGNC:4878): (hexosaminidase subunit alpha) This gene encodes a member of the glycosyl hydrolase 20 family of proteins. The encoded preproprotein is proteolytically processed to generate the alpha subunit of the lysosomal enzyme beta-hexosaminidase. This enzyme, together with the cofactor GM2 activator protein, catalyzes the degradation of the ganglioside GM2, and other molecules containing terminal N-acetyl hexosamines. Mutations in this gene lead to an accumulation of GM2 ganglioside in neurons, the underlying cause of neurodegenerative disorders termed the GM2 gangliosidoses, including Tay-Sachs disease (GM2-gangliosidosis type I). Alternative splicing results in multiple transcript variants, at least one of which encodes a preproprotein that is proteolytically processed. [provided by RefSeq, Jan 2016]

HEXA Gene-Disease associations (from GenCC):

Tay-Sachs disease
Inheritance: AR Classification: DEFINITIVE, STRONG Submitted by: Labcorp Genetics (formerly Invitae), Genomics England PanelApp, G2P, Myriad Women's Health, ClinGen

HEXA links:

ENSG00000260729 (HGNC:):

ENSG00000260729 links:

CELF6-AS1 (HGNC:58304):

CELF6-AS1 links:

Genome browser will be placed here

new If you want to explore the variant's impact on the transcript NM_000520.6, check out the Mutation Effect Viewer. This is especially useful for frameshift variants or if you want to visualize the effect of exon loss / intron retention.

ACMG classification

Classification was made for transcript

Our verdict: Pathogenic. The variant received 20 ACMG points.

PS3

PS3 evidence extracted from ClinVar submissions: SCV000263008: "Biosynthetic studies of the R499H alteration revealed the synthesis of an abnormal a-subunit which did not associate with the b-subunit. It was not processed into the mature lysosomal form and appeared to be retained and degraded in the endoplasmic reticulum, possibly due to misfolding. However some residual enzyme activity (~3%) was observed (Paw, 1990)."; SCV005690573: Functional studies demonstrate a damaging effect (retention of the Hex alpha-subunit in the ER and posterior degradation alongwith a lower value of the solvent-accessible surface area) (Paw et al., 1990).; SCV000617692: "Published functional studies demonstrate a damaging effect (retention of the Hex alpha-subunit in the ER and posterior degradation along with a lower value of the solvent-accessible surface area)" (PMID: 2140574)

PM1

In a hotspot region, there are 3 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 9 uncertain in NM_000520.6

PM5

Other missense variant is known to change same aminoacid residue: Variant chr15-72345477-G-A is described in ClinVar as Pathogenic. ClinVar VariationId is 3915.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

PP3

MetaRNN computational evidence supports a deleterious effect, 0.954

PP5

Variant 15-72345476-C-T is Pathogenic according to our data. Variant chr15-72345476-C-T is described in ClinVar as Pathogenic. ClinVar VariationId is 3899.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_000520.6. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
HEXA	NM_000520.6	MANE Select	c.1496G>A	p.Arg499His	missense	Exon 13 of 14	NP_000511.2	P06865-1
HEXA	NM_001318825.2		c.1529G>A	p.Arg510His	missense	Exon 13 of 14	NP_001305754.1	H3BP20
HEXA	NR_134869.3		n.1281G>A		non_coding_transcript_exon	Exon 11 of 11

Ensembl Transcripts

Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
HEXA	ENST00000268097.10	TSL:1 MANE Select	c.1496G>A	p.Arg499His	missense	Exon 13 of 14	ENSP00000268097.6	P06865-1
HEXA	ENST00000567159.5	TSL:1	c.1496G>A	p.Arg499His	missense	Exon 13 of 13	ENSP00000456489.1	H3BS10
ENSG00000260729	ENST00000379915.4	TSL:2	n.578G>A		non_coding_transcript_exon	Exon 5 of 16	ENSP00000478716.1	A0A087WUJ7

Frequencies

GnomAD3 genomes

AF:

0.0000328

AC:

AN:

152234

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.0000241

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

GnomAD2 exomes

AF:

0.0000557

AC:

AN:

251458

AF XY:

0.0000589

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.0000289

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.00

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.0000264

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.0000718

AC:

105

AN:

1461850

Hom.:

Cov.:

AF XY:

0.0000784

AC XY:

AN XY:

727232

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

33480

American (AMR)

AF:

0.00

AC:

AN:

44722

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26136

East Asian (EAS)

AF:

0.00

AC:

AN:

39700

South Asian (SAS)

AF:

0.000394

AC:

AN:

86256

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53404

Middle Eastern (MID)

AF:

0.000173

AC:

AN:

5768

European-Non Finnish (NFE)

AF:

0.0000621

AC:

AN:

1111990

Other (OTH)

AF:

0.0000166

AC:

AN:

60394

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.457

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Exome Het

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

GnomAD4 genome

AF:

0.0000328

AC:

AN:

152234

Hom.:

Cov.:

AF XY:

0.00

AC XY:

AN XY:

74372

show subpopulations

African (AFR)

AF:

0.0000241

AC:

AN:

41470

American (AMR)

AF:

0.00

AC:

AN:

15280

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3472

East Asian (EAS)

AF:

0.00

AC:

AN:

5204

South Asian (SAS)

AF:

0.00

AC:

AN:

4834

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10612

Middle Eastern (MID)

AF:

0.00

AC:

AN:

316

European-Non Finnish (NFE)

AF:

0.0000588

AC:

AN:

68040

Other (OTH)

AF:

0.00

AC:

AN:

2094

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.525

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Genome Het

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

Alfa

AF:

0.0000449

Hom.:

Bravo

AF:

0.0000189

ClinVar

ClinVar submissions

Significance:Pathogenic

Revision:criteria provided, multiple submitters, no conflicts

View on ClinVar

Pathogenic

VUS

Benign

Condition

Tay-Sachs disease (13)

not provided (3)

GM2-GANGLIOSIDOSIS, JUVENILE (1)

Inborn genetic diseases (1)

Computational scores

Source: dbNSFP v4.9

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Pathogenic

0.79

BayesDel_addAF

Pathogenic

0.37

BayesDel_noAF

Pathogenic

0.59

CADD

Pathogenic

(source)

DANN

Uncertain

1.0

DEOGEN2

Pathogenic

0.96

Eigen

Uncertain

0.64

Eigen_PC

Uncertain

0.47

FATHMM_MKL

Pathogenic

0.99

LIST_S2

Uncertain

0.90

M_CAP

Uncertain

0.25

MetaRNN

Pathogenic

0.95

MetaSVM

Pathogenic

1.1

MutationAssessor

Pathogenic

3.7

PhyloP100

7.6

PrimateAI

Uncertain

0.49

PROVEAN

Pathogenic

-4.6

REVEL

Pathogenic

0.89

Sift

Pathogenic

0.0

Sift4G

Pathogenic

0.0

RBP_binding_hub_radar

0.0

RBP_regulation_power_radar

1.7

Varity_R

0.84

gMVP

0.97

Mutation Taster

=5/95

disease causing (ClinVar)

(source)

Splicing

Name

Calibrated prediction

Score

Prediction

SpliceAI score (max)

0.040

Details are displayed if max score is > 0.2

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

MaxEntScan Visualizer can be used to analyze the impact of this mutation on the neighboring sequence.

Publications

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Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

Publications

ACMG classification

Variant Effect in Transcripts

RefSeq Transcripts

Ensembl Transcripts

Frequencies

Age Distribution

Age Distribution

ClinVar

Computational scores

Splicing

Publications

Other links and lift over