Intellectual disability - microarray and sequencing
Gene: ATP6V1A Green List (high evidence)Comment on list classification: New gene added by external expert and reviewed by curation team, enough evidence to support gene-disease association and relevance to this panel to rate this gene GreenCreated: 19 Nov 2018, 11:32 a.m.
From Sarah Leigh (Genomics England Curator) review 18 Nov 2018, 10:49 p.m Genetic epilepsy syndromes. Panel version: 0.917. Comment when marking as ready: Associated with phenotype in OMIM and not in Gen2Phen. At least 4 variants were identified in unrelated cases of Epileptic encephalopathy, infantile or early childhood, 3 618012, one variant (c.1045G>A, NM_001690.3, p.D349N) appear give gain of function results in in vitro analysis, whereas the others had loss of function. Two homozygous variants were reported in two unrelated cases of Cutis laxa, autosomal recessive, type IID 617403 who both had seizures as part of their phenotypes.
Comment on phenotypes: Monoallelic variants associated with Epileptic encephalopathy, infantile or early childhood, 3 618012 and biallelic variants associated with Cutis laxa, autosomal recessive, type IID 617403. Both phenotypes include seizures.Created: 19 Nov 2018, 11:06 a.m.
Green List (high evidence)
Heterozygous mutations in ATP6V1A cause Epileptic encephalopathy, infantile or early childhood, type 3 (MIM 618012).
PMID: 29668857 reports on 4 individuals from 4 families with de novo pathogenic variants in ATP6V1A. The phenotype was consistent with a developmental encephalopathy with epilepsy.
All patients were found to harbor missense variants. The variants resulted in altered lysosomal homeostasis, abnormal neuritogenesis and synaptic density. However in one of the variants tested (p.Asp100Tyr) pathogenicity was mediated by loss-of-function mechanism while for another (p.Asp349Asn) by gain-of-function mechanism.
Differences in severity were noted, with two variants (incl. Asp100Tyr) being associated with a more severe phenotype and the two other (incl. Asp349Asn) with milder degrees of ID and epilepsy.
Biallelic ATP6V1A mutations cause Cutis laxa type IID (MIM 617403). PMID: 28065471 is the first report on 3 individuals from 3 different families (2 of which were consanguineous). All patients were homozygous for ATP6V1A pathogenic variants. All three presented with hypotonia, one (or possibly two) with developmental delay and two with seizures although the developmental phenotype is not further commented on. (Additional patients described in the article harbored mutations in other genes and were not considered).
As a result, this gene can be considered for inclusion in this panel as green (or amber).
Sources: Literature, Expert ReviewCreated: 17 Nov 2018, 7:49 a.m.
Mode of inheritance
MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Phenotypes
# 618012 EPILEPTIC ENCEPHALOPATHY, INFANTILE OR EARLY CHILDHOOD, 3; IECEE3
Publications
Phenotypes for gene: ATP6V1A were changed from Epileptic encephalopathy, infantile or early childhood, 3 618012; Cutis laxa, autosomal recessive, type IID 617403 to Developmental and epileptic encephalopathy 93, OMIM:618012
Gene: atp6v1a has been classified as Green List (High Evidence).
Phenotypes for gene: ATP6V1A were changed from # 618012 EPILEPTIC ENCEPHALOPATHY, INFANTILE OR EARLY CHILDHOOD, 3; IECEE3 to Epileptic encephalopathy, infantile or early childhood, 3 618012; Cutis laxa, autosomal recessive, type IID 617403
gene: ATP6V1A was added gene: ATP6V1A was added to Intellectual disability. Sources: Literature,Expert Review Mode of inheritance for gene: ATP6V1A was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown Publications for gene: ATP6V1A were set to 29668857; 28065471 Phenotypes for gene: ATP6V1A were set to # 618012 EPILEPTIC ENCEPHALOPATHY, INFANTILE OR EARLY CHILDHOOD, 3; IECEE3 Penetrance for gene: ATP6V1A were set to unknown Review for gene: ATP6V1A was set to GREEN
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.