Intellectual disability - microarray and sequencing
Gene: PIGQ Green List (high evidence)Green List (high evidence)
The rating of this gene has been updated following NHS Genomic Medicine Service approval.Created: 9 Mar 2022, 3:40 p.m. | Last Modified: 9 Mar 2022, 3:40 p.m.
Panel Version: 3.1510
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: 17 Nov 2020, 10:09 a.m. | Last Modified: 17 Nov 2020, 10:09 a.m.
Panel Version: 3.550
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).Created: 16 Nov 2020, 5:40 p.m. | Last Modified: 16 Nov 2020, 5:40 p.m.
Panel Version: 3.549
Comment on list classification: There is enough evidence for this gene to be rated GREEN at the next major review.Created: 16 Nov 2020, 5:36 p.m. | Last Modified: 16 Nov 2020, 5:36 p.m.
Panel Version: 3.549
Mode of inheritance
BIALLELIC, autosomal or pseudoautosomal
Phenotypes
OMIM:618548
Green List (high evidence)
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: 3 Aug 2020, 10:37 p.m. | Last Modified: 3 Aug 2020, 10:37 p.m.
Panel Version: 3.226
Mode of inheritance
BIALLELIC, autosomal or pseudoautosomal
Phenotypes
Epileptic encephalopathy, early infantile, 77 (MIM #618548)
Publications
Red List (low evidence)
There is currently no evidence to suggest there is an association of this gene with intellectual disability.Created: 18 Dec 2017, 3:39 p.m.
Red List (low evidence)
Mode of inheritance
BIALLELIC, autosomal or pseudoautosomal
Phenotypes
SEVERE EARLY-ONSET EPILEPSY
Publications
Red List (low evidence)
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)
Phenotypes for gene: PIGQ were changed from Epileptic encephalopathy, early infantile 77, OMIM:618548 to Multiple congenital anomalies-hypotonia-seizures syndrome-4 OMIM:618548
Gene: pigq has been classified as Amber List (Moderate Evidence).
Tag for-review tag was added to gene: PIGQ.
Phenotypes for gene: PIGQ were changed from Epileptic encephalopathy, early infantile 77, 618548 to Epileptic encephalopathy, early infantile 77, OMIM:618548
Phenotypes for gene: PIGQ were changed from SEVERE EARLY-ONSET EPILEPSY; Epileptic encephalopathy, early infantile, 77, 618548 to Epileptic encephalopathy, early infantile 77, 618548
Publications for gene: PIGQ were set to 24463883
Phenotypes for gene: PIGQ were changed from SEVERE EARLY-ONSET EPILEPSY to SEVERE EARLY-ONSET EPILEPSY; Epileptic encephalopathy, early infantile, 77, 618548
12.03.2018: Due to major updates completed (Phase 1, 2 and 3), this panel was promoted to Version 2 in order to reflect the major updates since November 2017 which have resulted in reviews for 836 genes added by Genomics England Curators and the Clinical Team, 130 new Green genes added to the interpretation pipeline (from 751 to 881 Green genes), and the gene total has increased from 1879 to 1927.
The Gel status was updated for this whole panel
The Gel status was updated for this whole panel
PIGQ was added to Intellectual disabilitypanel. Sources: Expert Review Red
PIGQ was created by ellenmcdonagh
If promoting or demoting a gene, please provide comments to justify a decision to move it.
Genes included in a Genomics England gene panel for a rare disease category (green list) should fit the criteria A-E outlined below.
These guidelines were developed as a combination of the ClinGen DEFINITIVE evidence for a causal role of the gene in the disease(a), and the Developmental Disorder Genotype-Phenotype (DDG2P) CONFIRMED DD Gene evidence level(b) (please see the original references provided below for full details). These help provide a guideline for expert reviewers when assessing whether a gene should be on the green or the red list of a panel.
A. There are plausible disease-causing mutations(i) within, affecting or encompassing an interpretable functional region(ii) of this gene identified in multiple (>3) unrelated cases/families with the phenotype(iii).
OR
B. There are plausible disease-causing mutations(i) within, affecting or encompassing cis-regulatory elements convincingly affecting the expression of a single gene identified in multiple (>3) unrelated cases/families with the phenotype(iii).
OR
C. As definitions A or B but in 2 or 3 unrelated cases/families with the phenotype, with the addition of convincing bioinformatic or functional evidence of causation e.g. known inborn error of metabolism with mutation in orthologous gene which is known to have the relevant deficient enzymatic activity in other species; existence of an animal model which recapitulates the human phenotype.
AND
D. Evidence indicates that disease-causing mutations follow a Mendelian pattern of causation appropriate for reporting in a diagnostic setting(iv).
AND
E. No convincing evidence exists or has emerged that contradicts the role of the gene in the specified phenotype.
(i)Plausible disease-causing mutations: Recurrent de novo mutations convincingly affecting gene function. Rare, fully-penetrant mutations - relevant genotype never, or very rarely, seen in controls. (ii) Interpretable functional region: ORF in protein coding genes miRNA stem or loop. (iii) Phenotype: the rare disease category, as described in the eligibility statement. (iv) Intermediate penetrance genes should not be included.
It’s assumed that loss-of-function variants in this gene can cause the disease/phenotype unless an exception to this rule is known. We would like to collect information regarding exceptions. An example exception is the PCSK9 gene, where loss-of-function variants are not relevant for a hypercholesterolemia phenotype as they are associated with increased LDL-cholesterol uptake via LDLR (PMID: 25911073).
If a curated set of known-pathogenic variants is available for this gene-phenotype, please contact us at [email protected]
We classify loss-of-function variants as those with the following Sequence Ontology (SO) terms:
Term descriptions can be found on the PanelApp homepage and Ensembl.
If you are submitting this evaluation on behalf of a clinical laboratory please indicate whether you report variants in this gene as part of your current diagnostic practice by checking the box
Standardised terms were used to represent the gene-disease mode of inheritance, and were mapped to commonly used terms from the different sources. Below each of the terms is described, along with the equivalent commonly-used terms.
A variant on one allele of this gene can cause the disease, and imprinting has not been implicated.
A variant on the paternally-inherited allele of this gene can cause the disease, if the alternate allele is imprinted (function muted).
A variant on the maternally-inherited allele of this gene can cause the disease, if the alternate allele is imprinted (function muted).
A variant on one allele of this gene can cause the disease. This is the default used for autosomal dominant mode of inheritance where no knowledge of the imprinting status of the gene required to cause the disease is known. Mapped to the following commonly used terms from different sources: autosomal dominant, dominant, AD, DOMINANT.
A variant on both alleles of this gene is required to cause the disease. Mapped to the following commonly used terms from different sources: autosomal recessive, recessive, AR, RECESSIVE.
The disease can be caused by a variant on one or both alleles of this gene. Mapped to the following commonly used terms from different sources: autosomal recessive or autosomal dominant, recessive or dominant, AR/AD, AD/AR, DOMINANT/RECESSIVE, RECESSIVE/DOMINANT.
A variant on one allele of this gene can cause the disease, however a variant on both alleles of this gene can result in a more severe form of the disease/phenotype.
A variant in this gene can cause the disease in males as they have one X-chromosome allele, whereas a variant on both X-chromosome alleles is required to cause the disease in females. Mapped to the following commonly used term from different sources: X-linked recessive.
A variant in this gene can cause the disease in males as they have one X-chromosome allele. A variant on one allele of this gene may also cause the disease in females, though the disease/phenotype may be less severe and may have a later-onset than is seen in males. X-linked inactivation and mosaicism in different tissues complicate whether a female presents with the disease, and can change over their lifetime. This term is the default setting used for X-linked genes, where it is not known definitately whether females require a variant on each allele of this gene in order to be affected. Mapped to the following commonly used terms from different sources: X-linked dominant, x-linked, X-LINKED, X-linked.
The gene is in the mitochondrial genome and variants within this can cause this disease, maternally inherited. Mapped to the following commonly used term from different sources: Mitochondrial.
Mapped to the following commonly used terms from different sources: Unknown, NA, information not provided.
For example, if the mode of inheritance is digenic, please indicate this in the comments and which other gene is involved.