Fetal anomalies
Gene: FKBP8 Amber List (moderate evidence)Comment on list classification: Additional publication identified by Rhiannon Mellis (GOSH) describing a fetus with severe thoracolumbar scoliosis and caudal spinal cord agenesis and a homozygous (c.C572T:p.P191L) variant in FKBP8 (PMID: 29261186). Note the phenotype and MOI are distinct from other reports (PMID: 32969478).
FKBP8 remains a candidate gene and so maintaining Amber rating in anticipation of additional cases to corroborate pathogenicity.Created: 19 May 2021, 3:34 p.m. | Last Modified: 19 May 2021, 3:34 p.m.
Panel Version: 1.658
I don't know
Boissel et al 2018 (PMID: 29261186) suggest FKBP8 as a candidate gene for a fetus (19 weeks gestation) with severe thoracolumbar scoliosis with segmentation defects. Consanguineous parents. Homozygous, predicted-damaging missense variants found in this gene on WES.
Fkpb8 mutant mice show extensive fusion of vertebrae, so the authors postulate that the segmentation defects observed in the fetus are also caused by disruption of this gene.
NB this fetus was not reported to have spina bifida, in contrast to other cases in the literatureCreated: 27 Apr 2021, 6:07 p.m. | Last Modified: 27 Apr 2021, 6:07 p.m.
Panel Version: 1.641
Mode of inheritance
BIALLELIC, autosomal or pseudoautosomal
Phenotypes
Vertebral segmentation defects
Publications
I don't know
Comment on list classification: Changing rating from red to amber. 5 cases reported with plausible disease causing variants but only the FKBP8 gene looked at.Created: 2 Dec 2020, 6:49 p.m. | Last Modified: 2 Dec 2020, 6:49 p.m.
Panel Version: 1.120
Not associated with a phenotype in OMIM.
PMID: 32969478 - Tian et al 2020 - performed Sanger sequencing of FKBP8 on DNA samples from 472 spina bifida (SB) affected fetuses and 565 unaffected controls. 5 different rare heterozygous variants (MAF ≤ 0.001) were identified among the SB patients, while no deleterious rare variants were identified in the controls. 4 of the variants are missense, the other is a stop-gain. 2 cases were in white-Hispanic patients while the other 3 were non-white Hispanic. Functional studies showed that p.Glu140* affected FKBP8 localization to the mitochondria and impaired its interaction with BCL2 ultimately leading to an increase in cellular apoptosis. p.Ser3Leu, p.Lys315Asn and p.Ala292Ser variants decreased FKBP8 protein level. Gene expression was studied in mouse Fkbp8-/- embryos and found to be abnormal. Previous mouse models have shown neural tube defects.
Sufficient cases to rate green, but only the FKBP8 gene looked at so perhaps some caution required while further evidence is gathered.
Sources: LiteratureCreated: 2 Dec 2020, 6:47 p.m.
Mode of inheritance
MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Phenotypes
spina bifida HP:0002414
Publications
Mode of inheritance for gene: FKBP8 was changed from MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown to BOTH monoallelic and biallelic, autosomal or pseudoautosomal
Gene: fkbp8 has been classified as Amber List (Moderate Evidence).
Phenotypes for gene: FKBP8 were changed from spina bifida HP:0002414 to Spina bifida, HP:0002414; Vertebral segmentation defects
Publications for gene: FKBP8 were set to 32969478
Gene: fkbp8 has been classified as Amber List (Moderate Evidence).
gene: FKBP8 was added gene: FKBP8 was added to Fetal anomalies. Sources: Literature Mode of inheritance for gene: FKBP8 was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown Publications for gene: FKBP8 were set to 32969478 Phenotypes for gene: FKBP8 were set to spina bifida HP:0002414 Review for gene: FKBP8 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).
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.