Paediatric disorders - additional genes
Gene: PIGQ
The rating of this gene has been updated following NHS Genomic Medicine Service approval.Created: 10 Mar 2022, 3:53 p.m. | Last Modified: 10 Mar 2022, 3:53 p.m.
Panel Version: 1.96
Comment on list classification: There is enough evidence for this gene to be rated GREEN at the next major review.Created: 30 Nov 2020, 12:56 p.m. | Last Modified: 30 Nov 2020, 12:56 p.m.
Panel Version: 1.65
Comments from Konstantinos Varvagiannis
Homozygous or compound heterozygous mutations in PIGQ cause Epileptic encephalopathy, early infantile, 77 (MIM #618548). Johnstone et al (2020 - PMID: 32588908) describe the phenotype of 7 children (from 6 families) with biallelic PIGQ pathogenic variants. The authors also review the phenotype of 3 subjects previously reported in the literature (by Martin et al, Alazami et al, Starr et al - respective PMIDs: 24463883, 25558065, 31148362). Affected individuals displayed severe to profound global DD/ID and seizures with onset in the first year of life. There were variable other features incl. - among others - genitourinary, cardiac, skeletal, ophthalmological anomalies, gastrointestinal issues. Within the cohort there was significant morbidity/mortality. PIGQ encodes phosphatidylinositol glycan anchor biosynthesis class Q protein, playing a role (early) in the biosynthesis of the GPI-anchor. Several genes in the GPI biosynthesis pathway cause multi-system disease with DD/ID and seizures. Flow cytometry has been used in individuals with PIGQ-related disorder. Serum ALP was elevated in some (4) although - as the authors comment - elevations are more typical in disorders affecting later steps of GPI biosynthesis. More than 10 variants have been reported to date (missense / pLoF). Overall PIGQ can be considered for green rating in both ID and epilepsy gene panels.Created: 30 Nov 2020, 12:55 p.m. | Last Modified: 30 Nov 2020, 12:55 p.m.
Panel Version: 1.64
Comment on phenotypes: According to Joanna Peas-Welch (OMIM), Multiple congenital anomalies-hypotonia-seizures syndrome-4 (MCAHS4) will replace Epileptic encephalopathy, early infantile, 77, OMIM:618548 as the name for this phenotype (12/11/2020).Created: 30 Nov 2020, 12:53 p.m. | Last Modified: 30 Nov 2020, 12:53 p.m.
Panel Version: 1.64
Associated with relevant phenotype in OMIM and as possible Gen2Phen gene for severe early onset epilepsy. At least 11 variants reported in seven unrelated cases of multiple congenital anomalies-hypotonia-seizures syndrome-4 (MCAHS4)(Epileptic encephalopathy, early infantile, 77 618548)(OMIM:618548).
Sources: LiteratureCreated: 30 Nov 2020, 12:53 p.m.
Mode of inheritance
BIALLELIC, autosomal or pseudoautosomal
Phenotypes
Multiple congenital anomalies-hypotonia-seizures syndrome-4 OMIM:618548
Publications
Tag for-review was removed from gene: PIGQ.
Source Expert Review Green was added to PIGQ. Rating Changed from Amber List (moderate evidence) to Green List (high evidence)
Gene: pigq has been classified as Amber List (Moderate Evidence).
Phenotypes for gene: PIGQ were changed from Multiple congenital anomalies-hypotonia-seizures syndrome-4 OMIM:618548 to Multiple congenital anomalies-hypotonia-seizures syndrome-4 OMIM:618548
gene: PIGQ was added gene: PIGQ was added to Paediatric disorders - additional genes. Sources: Literature for-review tags were added to gene: PIGQ. Mode of inheritance for gene: PIGQ was set to BIALLELIC, autosomal or pseudoautosomal Publications for gene: PIGQ were set to 32588908; 24463883; 25558065; 31148362 Phenotypes for gene: PIGQ were set to Multiple congenital anomalies-hypotonia-seizures syndrome-4 OMIM:618548 Review for gene: PIGQ was set to GREEN