Intellectual disabilityGene: KCNK4 Amber List (moderate evidence)
Green List (high evidence)
Three unrelated individuals reported with a distinctive syndromic ID condition. As the variants are de novo, the fact that one of the variants was found in two of the individuals only adds weight to the evidence that the affected residue is functionally important.
Created: 8 Feb 2020, 9:24 a.m. | Last Modified: 8 Feb 2020, 9:24 a.m.
Panel Version: 3.0
Mode of inheritance
MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Facial dysmorphism, hypertrichosis, epilepsy, intellectual/developmental delay, and gingival overgrowth syndrome 618381
Variants in this GENE are reported as part of current diagnostic practice
As the 2 unrelated patients who have the same de novo variants have severe ID/DD and 3rd patient has low average ID, this gene will be kept as Amber until further evidence is available. Watchlist tag has been added as well.
Created: 19 Oct 2020, 3:03 p.m. | Last Modified: 19 Oct 2020, 3:03 p.m.
Panel Version: 3.461
Comment on list classification: New gene added by external expert and reviewed by curation team. Given an amber rating as there is currently only one report detailing 3 unrelated patients (2 Italian and 1 of European ancestry) who have variants (2 patients have the same missense variant and the third patient has a different missense variant). The paper also describe some in vitro cell studies. KCNK4 is classified as a possible disease causing gene for FHEIG (facial dysmorphism, hypertrichosis, epilepsy, intellectual disability/developmental delay, and gingival overgrowth) on Gene2Phenotype.
Created: 14 Feb 2019, 2:51 p.m.
I don't know
PMID: 30290154 reports on 3 unrelated individuals with de novo missense KCNK4 variants. All three individuals presented with developmental delay and epilepsy. Severe intellectual disability was a feature in two of these individuals while the third displayed low average intellectual functioning (IQ of 85). Other features common in all included facial dysmorphism (bushy eyebrows, long eyelashes, thin everted upper lip, micrognathia), generalized hypertrichosis and gingival overgrowth.
The two missense variants reported [(p.Ala172Glu) and (p.Ala244Pro)] occurred as de novo events in all subjects, while the first SNV was observed in 2 (of the 3) patients with severe intellectual disability.
Functional studies were suggestive of a gain-of-function effect. In line with this mechanism, Kcnk4 knockout mice did not seem to exhibit seizures, deficits in cognition or other neurodevelopmental phenotypes in a study conducted earlier and cited by the authors (PMID: 15175651).
As a result this gene can be considered for inclusion in the panel as amber (or green).
Sources: Literature, Expert Review
Created: 11 Oct 2018, 5:49 p.m.
Mode of inheritance
MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Neurodevelopmental delay; Intellectual disability; Seizures; Gingival overgrowth; Hypertrichosis
Mode of pathogenicity
Loss-of-function variants (as defined in pop up message) DO NOT cause this phenotype - please provide details in the comments
Tag watchlist tag was added to gene: KCNK4.
Phenotypes for gene: KCNK4 were changed from Neurodevelopmental delay; Intellectual disability; Seizures; Gingival overgrowth; Hypertrichosis to Facial dysmorphism, hypertrichosis, epilepsy, intellectual/developmental delay, and gingival overgrowth syndrome, 618381
Gene: kcnk4 has been classified as Amber List (Moderate Evidence).
gene: KCNK4 was added gene: KCNK4 was added to Intellectual disability. Sources: Literature,Expert Review Mode of inheritance for gene: KCNK4 was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown Publications for gene: KCNK4 were set to 30290154 Phenotypes for gene: KCNK4 were set to Neurodevelopmental delay; Intellectual disability; Seizures; Gingival overgrowth; Hypertrichosis Penetrance for gene: KCNK4 were set to unknown Mode of pathogenicity for gene: KCNK4 was set to Loss-of-function variants (as defined in pop up message) DO NOT cause this phenotype - please provide details in the comments Review for gene: KCNK4 was set to AMBER
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).
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).
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.
D. Evidence indicates that disease-causing mutations follow a Mendelian pattern of causation appropriate for reporting in a diagnostic setting(iv).
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.