Early onset or syndromic epilepsy
Gene: FUT8
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
AR congenital disorder of glycosylation with defective fucosylation - see poor growth, failure to thrive, hypotonia, skeletal anomalies, delayed psychomotor development with ID. Ng et al, 2018 - 3 unrelated children with a complex multisystem disorder - all had seizures. Hom or compound het variants were detected in them all, Western blot analysis from 2 patients showed no detectable FUT-8 protein.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
Congenital disorder of glycosylation with defective fucosylation, 618005
Publications
Comment when marking as ready: Associated with phenotype in OMIM and not in Gen2Phen. At least 4 variants identified in 3 unrelated cases, supportive segregation and in vitro data was also presented.Created: 18 Nov 2018, 10:57 p.m.
PMID: 29304374 reports on 3 unrelated individuals with biallelic pathogenic variants in FUT8.
Two of the patients were born to consanguineous parents and were found to be homozygous for stopgain variants (p.Arg239* in one family and p.Arg315* in the other). A third patient was compound heterozygous for a missense as well as a splice variant.
All three presented with similar phenotype consisting of polyhydramnios (2 out of 3), IUGR and failure to thrive with short stature (3/3), severe developmental delay (3/3) with microcephaly (3/3) and seizures (3/3). Variable respiratory problems were also noted in all.
Western blot demonstrated loss of FUT8 protein expression in one individual homozygous for a stopgain mutation as well as the patient who was compound heterozygous for the missense and the splice variant. The splice variant was further shown to produce a shorter transcript due to lack of exon 9, leading to an in-frame deletion of 59 residues critical for the protein function.
Additional studies confirmed the fucosylation defect compared to controls.
The authors note that while Fut8 knockout mice are born normal, 70% die within the first 3 days due to severe growth retardation and respiratory deficiency (similarly to what is observed in humans, though to a lesser extent).
As a result this gene can be considered for inclusion in this panel probably as green (3 unrelated families, strong additional functional data, consistent phenotype) or amber.
Sources: Literature, Expert ReviewCreated: 17 Nov 2018, 7:51 p.m.
Mode of inheritance
BIALLELIC, autosomal or pseudoautosomal
Phenotypes
Congenital disorder of glycosylation with defective fucosylation, 618005
Publications
Source Wessex and West Midlands GLH was added to FUT8.
Source NHS GMS was added to FUT8.
Phenotypes for gene: FUT8 were changed from Congenital disorder of glycosylation with defective fucosylation, 618005; Intellectual disability to Congenital disorder of glycosylation with defective fucosylation, 618005; seizures
Konstantinos Varvagiannis: PMID: 29304374 reports on 3 un
Phenotypes for gene: FUT8 were changed from Congenital disorder of glycosylation with defective fucosylation, 618005 to Congenital disorder of glycosylation with defective fucosylation, 618005; Intellectual disability
Gene: fut8 has been classified as Green List (High Evidence).
Gene: fut8 has been classified as Green List (High Evidence).
gene: FUT8 was added gene: FUT8 was added to Genetic epilepsy syndromes. Sources: Literature,Expert Review Mode of inheritance for gene: FUT8 was set to BIALLELIC, autosomal or pseudoautosomal Publications for gene: FUT8 were set to 29304374 Phenotypes for gene: FUT8 were set to Congenital disorder of glycosylation with defective fucosylation, 618005 Penetrance for gene: FUT8 were set to Complete Review for gene: FUT8 was set to GREEN