NM_000520.6:c.805+1G>A

Variant names:

Variant summary

Our verdict is Pathogenic. Variant got 18 ACMG points: 18P and 0B. PVS1PM2PP5_Very_Strong

The NM_000520.6(HEXA):c.805+1G>A variant causes a splice donor, intron change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.0000041 in 1,461,684 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. 3/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Pathogenic (★★).

Frequency

Genomes: not found (cov: 32)

Exomes 𝑓: 0.0000041 ( 0 hom. )

Consequence

HEXA
NM_000520.6 splice_donor, intron

Scores

Splicing: ADA: 1.000

Clinical Significance

Pathogenic criteria provided, multiple submitters, no conflicts P:7

Conservation

PhyloP100: 7.81

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 links:

ENSG00000261460 (HGNC:58304):

ENSG00000261460 links:

ENSG00000260729 (HGNC:):

ENSG00000260729 links:

Genome browser will be placed here

ACMG classification

Classification made for transcript

Verdict is Pathogenic. Variant got 18 ACMG points.

PVS1

Splicing +-2 bp (donor or acceptor) variant, LoF is a know mechanism of disease, No cryptic splice site detected. Exon removal results in frameshift change.

PM2

Very rare variant in population databases, with high coverage;

PP5

Variant 15-72350517-C-T is Pathogenic according to our data. Variant chr15-72350517-C-T is described in ClinVar as [Pathogenic]. Clinvar id is 3938.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr15-72350517-C-T is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	Effect	Exon rank	MANE	Protein	UniProt
HEXA	NM_000520.6 link	c.805+1G>A	splice_donor_variant, intron_variant	Intron 7 of 13	ENST00000268097.10	NP_000511.2	P06865-1A0A0S2Z3W3
HEXA	NM_001318825.2 link	c.838+1G>A	splice_donor_variant, intron_variant	Intron 7 of 13		NP_001305754.1	P06865H3BP20B4DVA7
HEXA	NR_134869.3 link	n.847+1G>A	splice_donor_variant, intron_variant	Intron 7 of 10

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
HEXA	ENST00000268097.10 link	c.805+1G>A		splice_donor_variant, intron_variant	Intron 7 of 13	1	NM_000520.6	ENSP00000268097.6		P06865-1
ENSG00000260729	ENST00000379915.4 link	n.413-4192G>A		intron_variant	Intron 3 of 15	2		ENSP00000478716.1		A0A087WUJ7

Frequencies

GnomAD3 genomes

Cov.:

GnomAD3 exomes

AF:

0.00000398

AC:

AN:

251436

Hom.:

AF XY:

0.00000736

AC XY:

AN XY:

135898

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.00

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:

0.00000879

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.00000410

AC:

AN:

1461684

Hom.:

Cov.:

AF XY:

0.00000550

AC XY:

AN XY:

727138

show subpopulations

Gnomad4 AFR exome

AF:

0.00

Gnomad4 AMR exome

AF:

0.00

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:

0.00000540

Gnomad4 OTH exome

AF:

0.00

GnomAD4 genome

Cov.:

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:7

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

Tay-Sachs disease

Pathogenic:6

Mar 17, 2017

Natera, Inc.

Significance: Pathogenic

Review Status: no assertion criteria provided

Collection Method: clinical testing

- -

May 21, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change affects a donor splice site in intron 7 of the HEXA gene. It is expected to disrupt RNA splicing. Variants that disrupt the donor or acceptor splice site typically lead to a loss of protein function (PMID: 16199547), and loss-of-function variants in HEXA are known to be pathogenic (PMID: 1833974, 8490625). This variant is present in population databases (rs121907980, gnomAD 0.0009%). Disruption of this splice site has been observed in individual(s) with Tay-Sachs disease (PMID: 1483696, 22789865). It is commonly reported in individuals of French Canadian ancestry (PMID: 1483696). This variant is also known as IVS7+1G>A. ClinVar contains an entry for this variant (Variation ID: 3938). Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. For these reasons, this variant has been classified as Pathogenic. -

Nov 12, 2019

Myriad Genetics, Inc.

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

NM_000520.4(HEXA):c.805+1G>A(aka IVS7+1G>A) is classified as pathogenic in the context of hexosaminidase A deficiency and is associated with Tay-Sachs disease. Sources cited for classification include the following: PMID 22789865, 1483696 and 7717398. Classification of NM_000520.4(HEXA):c.805+1G>A(aka IVS7+1G>A) is based on the following criteria: The variant is located at a canonical splice site, is expected to disrupt gene function and is reported in individuals with the relevant phenotype. Please note: this variant was assessed in the context of healthy population screening. -

Dec 01, 1992

OMIM

Significance: Pathogenic

Review Status: no assertion criteria provided

Collection Method: literature only

- -

May 18, 2022

Fulgent Genetics, Fulgent Genetics

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Dec 14, 2017

Women's Health and Genetics/Laboratory Corporation of America, LabCorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Variant summary: The HEXA c.805+1G>A variant involves the alteration of a conserved intronic nucleotide and 5/5 splice prediction tools predict a significant impact on normal splicing, which is supported by a functional study (Hechtman_1992). In addition, Gort_2012 observed very little (<10%) HEXA activity in a compound heterozygote affected individual. This variant was found in 1/246234 control chromosomes at a frequency of 0.0000041, which does not exceed the estimated maximal expected allele frequency of a pathogenic HEXA variant (0.0013975). Multiple publications have cited the variant in affected compound heterozygote individuals, predominantly French Canadians. In addition, a clinical diagnostic laboratory and reputable database classified this variant as likely pathogenic/pathogenic. Taken together, this variant is classified as pathogenic. -

HEXA-related disorder

Pathogenic:1

Feb 09, 2024

PreventionGenetics, part of Exact Sciences

Significance: Pathogenic

Review Status: no assertion criteria provided

Collection Method: clinical testing

The HEXA c.805+1G>A variant is predicted to disrupt the GT donor site and interfere with normal splicing. This variant was reported in the compound heterozygous state in multiple individuals with Tay-Sachs disease and was also shown to segregate with disease in three unrelated families (Figure 2, Hechtman et al. 1992. PubMed ID: 1483696; Table 2, Triggs-Raine et al. 1995. PubMed ID: 7717398; Table 1, Gort et al. 2012. PubMed ID: 22789865). Experimental studies suggest this variant impacts protein function showing little to no HexA activity in both serum and cultured human fibroblasts of the affected probands (Hechtman et al. 1992. PubMed ID: 1483696; Gort et al. 2012. PubMed ID: 22789865). This variant was found frequently in individuals of French Canadian ancestry (Hechtman et al. 1992. PubMed ID: 1483696). This variant is reported in 0.00088% of alleles in individuals of European (Non-Finnish) descent in gnomAD. Variants that disrupt the consensus splice donor site in HEXA are expected to be pathogenic. Taken together, this variant is interpreted as pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

BayesDel_addAF

Pathogenic

0.63

BayesDel_noAF

Pathogenic

0.45

CADD

Pathogenic

DANN

Uncertain

1.0

Eigen

Pathogenic

1.2

Eigen_PC

Pathogenic

1.1

FATHMM_MKL

Pathogenic

1.0

GERP RS

5.9

RBP_binding_hub_radar

0.0

RBP_regulation_power_radar

2.7

Splicing

Name

Calibrated prediction

Score

Prediction

dbscSNV1_ADA

Pathogenic

1.0

dbscSNV1_RF

Pathogenic

0.94

SpliceAI score (max)

1.0

Details are displayed if max score is > 0.2

DS_DL_spliceai

1.0

Position offset: 1

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

Publications

LitVar

Below is the list of publications found by LitVar. It may be empty.

Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

LitVar

Other links and lift over