Intellectual disabilityGene: KATNB1 Amber List (moderate evidence)
Comment on list classification: Updated rating from Grey to Amber. Gene was added to the ID panel and rated Green by Konstantinos Varvagiannis. Although there are 3 publications reporting biallelic variants, the ID phenotype is variable with only mild cognitive delay in some cases (PMID:25521378), and psychomotor delay in another (PMID:26640080). KATNB1 is Green on the 'malformations of cortical development' panel. Therefore have rated Amber on the ID panel awaiting further cases.
Created: 21 Sep 2019, 9:18 a.m. | Last Modified: 21 Sep 2019, 9:18 a.m.
Panel Version: 2.1046
Summary of evidence (for details refer to Konstantinos Varvagiannis' review): 3 publications reporting patients with biallelic KATNB1 variants:
PMID:25521378. Mishra-Gorur et al. 2014 report 5 families with malformations of cortical development and homozygous KATNB1 variants. In many families homozygous variants in additional genes were also reported. Congnitive delay was mild to severe in all patients: Supplementary Table S1.
PMID:25521379. Hu et al., 2014 report 3 unrelated Middle Eastern families with microcephaly, Global DD and seizures, and 3 different homozygous variants in KATNB1.
PMID:26640080. Yigit el al. 2016 report a homozygous acceptor splice-site intronic KATNB1 variant in a 5 year old Turkish girl born to consanguineous cousins, who presented with congenital microcephaly, lissencephaly, short stature, polysyndactyly, dental abnormalities and psychomotor delay.
Created: 21 Sep 2019, 9:14 a.m. | Last Modified: 21 Sep 2019, 9:14 a.m.
Panel Version: 2.1044
Green List (high evidence)
Biallelic pathogenic KATNB1 variants cause Lissencephaly 6, with microcephaly (MIM 616212). At least 13 affected individuals from 9 (mostly consanguineous) families have probably been reported in the following articles:
- Mishra-Gorur et al. (2014 - PMID: 25521378) [7 individuals from 5 unrelated families]
- Hu et al. (2014 - PMID: 25521379) [5 individuals from 3 families]
- Yigit el al. (2016 - PMID: 26640080) [1 subject born to consanguineous parents]
The phenotype appears to be relevant to the current panel. Several different variants have been reported to date. Extensive studies as for the impact of mutations at the cellular level as well as animal models (zebrafish, mouse, drosophila) support involvement of KATNB1. These arguments, provided mainly by the first two studies, are summarized in the respective OMIM entry for the disorder : https://omim.org/entry/616212 (variants and their effect are discussed in the entry for KATNB1 - https://omim.org/entry/602703).
The individual reported by Yigit el al. was a 5 year-old girl with - among others - severely delayed psychomotor development. The child was found to harbor a homozygous splice site variant (removing the acceptor AG signature). Confirmation of the variant and segregation studies were performed with Sanger sequencing. cDNA studies were carried out and demonstrated aberrant splicing.
KATNB1 is not associated with any disorder in G2P.
The gene is included in panels for ID offered by several diagnostic laboratories (incl. Radboudumc).
As a result, this gene can be considered for inclusion in the current panel probably as green (or amber).
Sources: Literature, Radboud University Medical Center, Nijmegen
Created: 31 Aug 2019, 10:46 a.m.
Mode of inheritance
BIALLELIC, autosomal or pseudoautosomal
Lissencephaly 6, with microcephaly (MIM 616212)
Variants in this GENE are reported as part of current diagnostic practice
Gene: katnb1 has been classified as Amber List (Moderate Evidence).
Phenotypes for gene: KATNB1 were changed from Lissencephaly 6, with microcephaly (MIM 616212) to Lissencephaly 6, with microcephaly, MIM 616212
gene: KATNB1 was added gene: KATNB1 was added to Intellectual disability. Sources: Literature,Radboud University Medical Center, Nijmegen Mode of inheritance for gene: KATNB1 was set to BIALLELIC, autosomal or pseudoautosomal Publications for gene: KATNB1 were set to 25521378; 25521379; 26640080 Phenotypes for gene: KATNB1 were set to Lissencephaly 6, with microcephaly (MIM 616212) Penetrance for gene: KATNB1 were set to Complete Review for gene: KATNB1 was set to GREEN gene: KATNB1 was marked as current diagnostic
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.