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Genetic epilepsy syndromes

Gene: HEXA

Green List (high evidence)

HEXA (hexosaminidase subunit alpha)
EnsemblGeneIds (GRCh38): ENSG00000213614
EnsemblGeneIds (GRCh37): ENSG00000213614
OMIM: 606869, Gene2Phenotype
HEXA is in 17 panels

4 reviews

Rebecca Foulger (Genomics England curator)

I don't know

Review and rating collated by Tracy Lester (Oxford Medical Genetics Laboratories Oxford University Hospitals NHS Foundation Trust, 2019_02_06) on behalf of Wessex and West Midlands GLH for GMS Neurology specialist test group, for Clinical Indication R59 'Early onset or syndromic epilepsy'. Review contributors: John Taylor and Helen Lord. Suggested gene rating: Green.
Created: 6 Aug 2019, 8:38 p.m. | Last Modified: 6 Aug 2019, 8:38 p.m.
Panel Version: 1.189

Tracy Lester (Genetics laboratory, Oxford UK)

Green List (high evidence)

AR Tay Sachs, GM2-gangliosidosis, HEXA pseudodeficiency. Tay Sachs - progressive neurodegenerative disorder which in the classic infantile form is fatal by age 2-3 years. Infant onset of developmental retardation, followed by paralysis, dementia, blindness then death. No mention in the clinical features part of OMIM that any of these cases had seizures. Refs from panel app: Gowda et al, 2018 - 3 year old boy who had a febrile episode and developed myoclonic jerks - hom missense variant detected. Richard et al, 1995 - Non Jewish child - seizures present and is compound het for a missense and a splice site variant. Najmabadi et al, 2011 - Patient M165 - HEXA variant (hom) - had seizures. Are seizures a common feature??
Created: 6 Aug 2019, 8:31 p.m. | Last Modified: 6 Aug 2019, 8:31 p.m.
Panel Version: 1.188

Mode of inheritance
BIALLELIC, autosomal or pseudoautosomal

Phenotypes
GM2-gangliosidosis, several forms, 272800; Tay-Sachs disease, 272800; [Hex A pseudodeficiency], 272800

Publications

Ivone Leong (Genomics England Curator)

Tay-Sachs disease is rare in the general population but has increased frequency in Ashkenazi Jews. Many of the papers do not specify whether patients have seizures/epilpsy and many report on the patient's phenotype as classic infantile (seizures can be a symptom), juvenile or adult late-onset (seizures can be a symptom), which may or may not necessarily mean patients have seizures. I have only included studies that mention seizures/epilepsy specifically.
Three studies have reported 3 patients with different variants in HEXA gene who have seizures (PMID: 30006889, 21937992, 7551830). PMID: 14972682 describe a mouse model of HEXA which also exhibited seizure/epilpsy phenotype.
Created: 22 Nov 2018, 1:52 p.m.
Comment on list classification: Promoted from Amber to Green as seizures is a phenotype of
Tay-Sachs disease is confirmed to be associated with this gene by both OMIM and Gene2Phenotype and seizures is listed in both of these databases.
Created: 15 Nov 2018, 11:43 a.m.

Zornitza Stark (Australian Genomics)

Green List (high evidence)

Seizures are part of the phenotype in this metabolic disorder.
Created: 15 Aug 2018, 1:04 a.m.

Mode of inheritance
BIALLELIC, autosomal or pseudoautosomal

Phenotypes
Tay-Sachs disease, MIM#272800

Variants in this GENE are reported as part of current diagnostic practice

History Filter Activity

6 Aug 2019, Gel status: 3

Added New Source

Rebecca Foulger (Genomics England curator)

Source Wessex and West Midlands GLH was added to HEXA.

6 Aug 2019, Gel status: 3

Added New Source

Rebecca Foulger (Genomics England curator)

Source NHS GMS was added to HEXA.

9 Jan 2019, Gel status: 3

Set Phenotypes

Louise Daugherty (Genomics England Curator)

Phenotypes for gene: HEXA were changed from Tay-Sachs disease, 272800 to GM2-gangliosidosis, several forms, 272800; Tay-Sachs disease, 272800

11 Dec 2018, Gel status: 3

Panel promoted to version 1.0

Sarah Leigh (Genomics England Curator)

Zornitza Stark: Seizures are part of the pheno

22 Nov 2018, Gel status: 3

Set publications

Ivone Leong (Genomics England Curator)

Publications for gene: HEXA were set to

15 Nov 2018, Gel status: 3

Entity classified by Genomics England curator

Ivone Leong (Genomics England Curator)

Gene: hexa has been classified as Green List (High Evidence).

15 Nov 2018, Gel status: 3

Entity classified by Genomics England curator

Ivone Leong (Genomics England Curator)

Gene: hexa has been classified as Green List (High Evidence).

15 Nov 2018, Gel status: 2

Set mode of inheritance

Ivone Leong (Genomics England Curator)

Mode of inheritance for gene: HEXA was changed from BIALLELIC, autosomal or pseudoautosomal to BIALLELIC, autosomal or pseudoautosomal

15 Nov 2018, Gel status: 2

Set mode of inheritance

Ivone Leong (Genomics England Curator)

Mode of inheritance for gene: HEXA was changed from to BIALLELIC, autosomal or pseudoautosomal

15 Nov 2018, Gel status: 2

Set Phenotypes

Ivone Leong (Genomics England Curator)

Phenotypes for gene: HEXA were changed from to Tay-Sachs disease, 272800

25 Jun 2018, Gel status: 2

Added New Source

Sarah Leigh (Genomics England Curator)

Expert Review Amber was added to HEXA. Panel: Genetic Epilepsy Syndromes

25 Jun 2018, Gel status: 1

Added New Source

Sarah Leigh (Genomics England Curator)

HEXA was added to Genetic Epilepsy Syndromes panel. Sources: Victorian Clinical Genetics Services

25 Jun 2018, Gel status: 1

Created

Sarah Leigh (Genomics England Curator)

HEXA was created by Sarah Leigh