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Early onset or syndromic epilepsy v2.491 PIGK Sarah Leigh Tag for-review was removed from gene: PIGK.
Early onset or syndromic epilepsy v2.491 PIGK Sarah Leigh commented on gene: PIGK: The rating of this gene has been updated following NHS Genomic Medicine Service approval.
Early onset or syndromic epilepsy v2.490 PIGK Sarah Leigh Source Expert Review Green was added to PIGK.
Rating Changed from Amber List (moderate evidence) to Green List (high evidence)
Early onset or syndromic epilepsy v2.284 PIGK Sarah Leigh Phenotypes for gene: PIGK were changed from Neurodevelopmental disorder with hypotonia and cerebellar atrophy, with or without seizures 618879 to Neurodevelopmental disorder with hypotonia and cerebellar atrophy, with or without seizures OMIM:618879
Early onset or syndromic epilepsy v2.281 PIGK Helen Lord reviewed gene: PIGK: Rating: GREEN; Mode of pathogenicity: None; Publications: 32220290; Phenotypes: ; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Early onset or syndromic epilepsy v2.181 PIGK Arina Puzriakova Classified gene: PIGK as Amber List (moderate evidence)
Early onset or syndromic epilepsy v2.181 PIGK Arina Puzriakova Added comment: Comment on list classification: Changed rating to Amber so that Green genes on this panel reflect the NHS signed-off version. This will be reviewed at the next GMS panel update (added 'for-review' tag).
Early onset or syndromic epilepsy v2.181 PIGK Arina Puzriakova Gene: pigk has been classified as Amber List (Moderate Evidence).
Early onset or syndromic epilepsy v2.180 PIGK Arina Puzriakova Tag for-review tag was added to gene: PIGK.
Early onset or syndromic epilepsy v2.95 PIGK Sarah Leigh Classified gene: PIGK as Green List (high evidence)
Early onset or syndromic epilepsy v2.95 PIGK Sarah Leigh Added comment: Comment on list classification: Zornitza Stark loaded PIGK as a green gene on Intellectual disability (https://panelapp.genomicsengland.co.uk/panels/285/gene/PIGK/#!review). and suggested that it was also suitable for the Genetic epilepsy syndromes panel.
Early onset or syndromic epilepsy v2.95 PIGK Sarah Leigh Gene: pigk has been classified as Green List (High Evidence).
Early onset or syndromic epilepsy v2.94 PIGK Sarah Leigh gene: PIGK was added
gene: PIGK was added to Genetic epilepsy syndromes. Sources: Expert list
Mode of inheritance for gene: PIGK was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: PIGK were set to 32220290
Phenotypes for gene: PIGK were set to Neurodevelopmental disorder with hypotonia and cerebellar atrophy, with or without seizures 618879
Review for gene: PIGK was set to GREEN
Added comment: Associated with relevant phenotype in OMIM and as probable Gen2Phen gene for PIGK-associated Neurodevelopmental Syndrome. At least 7 variants reported in at least 5 unrelated cases with seizures.
Sources: Expert list
Early onset or syndromic epilepsy v1.193 PIGU Konstantinos Varvagiannis gene: PIGU was added
gene: PIGU was added to Genetic epilepsy syndromes. Sources: Literature
Mode of inheritance for gene: PIGU was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: PIGU were set to 31353022
Phenotypes for gene: PIGU were set to Global developmental delay; Intellectual disability; Seizures; Cerebral atrophy; Cerebellar hypoplasia; Scoliosis
Penetrance for gene: PIGU were set to Complete
Review for gene: PIGU was set to GREEN
Added comment: Knaus et al. (2019 - PMID: 31353022) report on 5 affected individuals (from 3 unrelated families) with biallelic pathogenic PIGU variants.

Common features included tone abnormalities, global DD, ID, seizures, CNS anomalies (cerebral atrophy and/or cerebellar hypoplasia), scoliosis. Affected individuals presented also with facial similarities. DD/ID were universal features and their severity appears to be relevant to the panel. Seizures were also reported in all individuals (myoclonic in 3, for whom this was specified). ALP was normal in all.

Three individuals from 2 non-consanguineous families (one from Norway, the other not specified) were homozygous for a missense variant NM_080476.4:c.1149C>A (or p.Asn383Lys) present with an AF of 7/277197 in Europeans. Two individuals born to consanguineous parents from Turkey were homozygous for another missense variant (c.209T>A or p.Ile70Lys - same RefSeq).

Segregation analyses in parents and unaffected sibs were carried out.

PIGU encodes a subunit of the GPI transaminidase, a heteropentameric complex (other subunits encoded by PIGK, PIGS, PIGT and GPAA1) that mediates attachment in the endoplasmic reticulum of glycosylphosphatidylinositol (GPI) to the C-termini of proteins which are subsequently anchored to the cell surface.

Pathogenic variants in 18 of 29 genes implicated in biosynthesis of the GPI anchor have been identified as a cause of GPI biosynthesis disorders, with ID and seizures as principal features. Mutations in other genes encoding components of the GPI transaminidase complex (GPAA1, PIGT and PIGS) lead to neurodevelopmental disorders.

Functional impairment of PIGU was supported by flow-cytometric analysis showing significant reduction of cell surface expression of GPI anchored proteins (mainly FLAER, CD16 and CD24) on granulocytes from affected individuals. In addition accumulation of free GPI anchors on the cell surface of B cells from affected individuals further suggested deficiency of the GPI transaminidase.

Transient expression of mutant (Asn383Lys) protein failed to rescue expression of GPI-APs to the same extent as wt in a CHO cell line deficient for PIGU.

Feature analysis demonstrated similarities among individuals with mutations in other genes of the GPI transamidase complex (GPAA1 and PIGT) as well as with GPI biosynthesis disorders. Facial analysis was also suggestive of facial similarities between individuals with GPAA1 and PIGU mutations.

PIGU is not associated with any phenotype in OMIM or G2P.

As a result this gene can be considered for inclusion in the ID and epilepsy panels probably as green (3 families, ID of relevant severity and seizures in all affected individuals, known group of disorders and supportive evidence) or amber.
Sources: Literature