Intellectual disability - microarray and sequencing
Gene: CCDC88A Amber List (moderate evidence)Comment on list classification: This gene has been upgraded from Red to Amber based on the external reviews by Konstantinos Varvagiannis and Zornitza Stark.Created: 3 Sep 2020, 4:50 p.m. | Last Modified: 3 Sep 2020, 4:50 p.m.
Panel Version: 3.284
I don't know
As suggested in a previous review this gene can possibly be considered for upgrade to amber based on PMID: 26917597 (3 individuals from a broader consanguineous pedigree, all homozygous for a nonsense variant shown to escape NMD but producing a severely truncated protein. Mouse knockout phenotype mimics the human).
PMID: 30392057 is probably a second report on the phenotype related to biallelic CCDC88A mutations. 2 sibs born to consanguineous parents from Saudi Arabia are described very briefly (epilepsy, ID, optic atrophy and pedal edema). Both sibs were homozygous for a novel truncating variant [c.1292G>A p.(Trp431*)].
NB. Apart from the poor phenotypic description the article has a few additional issues :
- The reference sequence is not mentioned but c.1292G>A would correspond to Trp431* whether NM_001135597/NM_018084/NM_001254943 is used [http://www.mutationtaster.org/cgi-bin/MutationTaster/MT_ChrPos.cgi?chromosome=2&position=55570825&ref=C&alt=T]C&alt=T]. The sequence from the chromatograms provided maps only to CCDC88A and corresponds to the predicted amino acid change (using UCSC's Blat).
- The 3 additional variants in Table 1 (ref: Ekici et al. 2010) probably correspond to CCDC88C but not CCDC88A [correct reference for these variants : Ekici et al., 2010 - PMID: 21031079].
The corresponding phenotype in OMIM is # 617507 PEHO-like syndrome.
Overall this gene can be considered for upgrade to amber until further cases are published.Created: 19 Nov 2018, 1:42 p.m.
Mode of inheritance
BIALLELIC, autosomal or pseudoautosomal
Phenotypes
?PEHO syndrome-like, 617507
Publications
I don't know
Two unrelated families now plus mouse model.Created: 1 Feb 2020, 12:55 a.m. | Last Modified: 1 Feb 2020, 12:55 a.m.
Panel Version: 3.0
Single family reported in the literature so far with functional evidence. Merits Amber status in anticipation of further cases being reported.Created: 22 Jun 2018, 10:22 a.m.
Mode of inheritance
BIALLELIC, autosomal or pseudoautosomal
Phenotypes
PEHO syndrome
Publications
Variants in this GENE are reported as part of current diagnostic practice
Gene: ccdc88a has been classified as Amber List (Moderate Evidence).
Source Victorian Clinical Genetics Services was added to CCDC88A.
CCDC88A was added to Intellectual disability panel. Sources: Literature
CCDC88A was created by Zornitza Stark
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.