CIAO1 and MMS19 deficiency: A lethal neurodegenerative phenotype caused by cytosolic Fe-S cluster protein assembly disorders.

PURPOSE: The functionality of many cellular proteins depends on cofactors; yet, they have only been implicated in a minority of Mendelian diseases. Here, we describe the first 2 inherited disorders of the cytosolic iron-sulfur protein assembly system. METHODS: Genetic testing via genome sequencing was applied to identify the underlying disease cause in 3 patients with microcephaly, congenital brain malformations, progressive developmental and neurologic impairments, recurrent infections, and a fatal outcome. Studies in patient-derived skin fibroblasts and zebrafish models were performed to investigate the biochemical and cellular consequences. RESULTS: Metabolic analysis showed elevated uracil and thymine levels in body fluids but no pathogenic variants in DPYD, encoding dihydropyrimidine dehydrogenase. Genome sequencing identified compound heterozygosity in 2 patients for missense variants in CIAO1, encoding cytosolic iron-sulfur assembly component 1, and homozygosity for an in-frame 3-nucleotide deletion in MMS19, encoding the MMS19 homolog, cytosolic iron-sulfur assembly component, in the third patient. Profound alterations in the proteome, metabolome, and lipidome were observed in patient-derived fibroblasts. We confirmed the detrimental effect of deficiencies in CIAO1 and MMS19 in zebrafish models. CONCLUSION: A general failure of cytosolic and nuclear iron-sulfur protein maturation caused pleiotropic effects. The critical function of the cytosolic iron-sulfur protein assembly machinery for antiviral host defense may well explain the recurrent severe infections occurring in our patients.

Deregulated Regulators: Disease-Causing cis Variants in Transcription Factor Genes.

Whole-genome sequencing is accelerating identification of noncoding variants that disrupt gene expression, although reports of such regulatory variants implicated in disease remain rare. A notable subset of described variants affect transcription factor (TF) genes and other master regulators in cis through dosage effects. From the literature, we compiled 46 regulatory variants linked to 40 TF genes implicated in rare diseases. We discuss the genomic geography of these variants and the evidence presented for their potential pathogenicity. To help advance research on candidate disease variants into the literature, we introduce an evidence framework specific to regulatory variants, which are under-represented in current variant classification guidelines. The clinical research interpretation of patient genomes may be advanced by considering regulatory variants, particularly those that deregulate TF genes.

RevUP: an online scoring system for regulatory variants implicated in rare diseases.

SUMMARY: To address the difficulty in assessing the implication of regulatory variants in diseases, a scoring scheme previously published allows the calculation of the Regulatory Variant Evidence score (RVE-score). The score represents the accumulated evidence for a causative role of a regulatory variant in a disease. Regulatory Evidence for Variants Underlying Phenotypes was built to calculate the RVE-score of regulatory variants, based on the 24 criteria, with a hybrid approach combining information retrieved from public databases and user input. AVAILABILITY AND IMPLEMENTATION: RevUP is freely available at http://www.revup-classifier.ca. The source code is available at https://github.com/wassermanlab/revup. SUPPLEMENTARY INFORMATION: Supplementary data are available at Bioinformatics online.

JASPAR 2020: update of the open-access database of transcription factor binding profiles.

JASPAR (http://jaspar.genereg.net) is an open-access database of curated, non-redundant transcription factor (TF)-binding profiles stored as position frequency matrices (PFMs) for TFs across multiple species in six taxonomic groups. In this 8th release of JASPAR, the CORE collection has been expanded with 245 new PFMs (169 for vertebrates, 42 for plants, 17 for nematodes, 10 for insects, and 7 for fungi), and 156 PFMs were updated (125 for vertebrates, 28 for plants and 3 for insects). These new profiles represent an 18% expansion compared to the previous release. JASPAR 2020 comes with a novel collection of unvalidated TF-binding profiles for which our curators did not find orthogonal supporting evidence in the literature. This collection has a dedicated web form to engage the community in the curation of unvalidated TF-binding profiles. Moreover, we created a Q&A forum to ease the communication between the user community and JASPAR curators. Finally, we updated the genomic tracks, inference tool, and TF-binding profile similarity clusters. All the data is available through the JASPAR website, its associated RESTful API, and through the JASPAR2020 R/Bioconductor package.

Canine neuropathies: powerful spontaneous models for human hereditary sensory neuropathies.

In humans, hereditary sensory neuropathies (HSN), also known as hereditary sensory and autonomic neuropathies (HSAN), constitute a clinically and genetically heterogeneous group of disorders characterized by progressive sensory loss, often accompanied by chronic skin ulcerations and nail dystrophic changes. To date, although around 20 genes have already been discovered, they do not explain the genetic causes of all patients. In dogs, similar neuropathies are also diagnosed, several breeds being predisposed to specific forms of the disease. Indeed, the breed specificity of most canine genetic diseases is due to the small numbers of founders and high levels of inbreeding. Recent knowledge and tools developed to study the canine genome efficiently allows deciphering the genetic bases of such diseases. To date, a dozen breeds are recognized to develop specific HSN. For the Border collie and hunting dog breeds, the genes involved have recently been discovered. Other affected breeds thus constitute potential genetic models, with new genes to be found in dogs that can be considered as candidate genes for human HSAN/HSN. Here, we review the different forms of human and canine HSAN/HSN and we present a novel form in Fox terrier cases, highlighting the advantages of the dog model for such rare human diseases.

A Point Mutation in a lincRNA Upstream of GDNF Is Associated to a Canine Insensitivity to Pain: A Spontaneous Model for Human Sensory Neuropathies.

Human Hereditary Sensory Autonomic Neuropathies (HSANs) are characterized by insensitivity to pain, sometimes combined with self-mutilation. Strikingly, several sporting dog breeds are particularly affected by such neuropathies. Clinical signs appear in young puppies and consist of acral analgesia, with or without sudden intense licking, biting and severe self-mutilation of the feet, whereas proprioception, motor abilities and spinal reflexes remain intact. Through a Genome Wide Association Study (GWAS) with 24 affected and 30 unaffected sporting dogs using the Canine HD 170K SNP array (Illumina), we identified a 1.8 Mb homozygous locus on canine chromosome 4 (adj. p-val = 2.5x10-6). Targeted high-throughput sequencing of this locus in 4 affected and 4 unaffected dogs identified 478 variants. Only one variant perfectly segregated with the expected recessive inheritance in 300 sporting dogs of known clinical status, while it was never present in 900 unaffected dogs from 130 other breeds. This variant, located 90 kb upstream of the GDNF gene, a highly relevant neurotrophic factor candidate gene, lies in a long intergenic non-coding RNAs (lincRNA), GDNF-AS. Using human comparative genomic analysis, we observed that the canine variant maps onto an enhancer element. Quantitative RT-PCR of dorsal root ganglia RNAs of affected dogs showed a significant decrease of both GDNF mRNA and GDNF-AS expression levels (respectively 60% and 80%), as compared to unaffected dogs. We thus performed gel shift assays (EMSA) that reveal that the canine variant significantly alters the binding of regulatory elements. Altogether, these results allowed the identification in dogs of GDNF as a relevant candidate for human HSAN and insensitivity to pain, but also shed light on the regulation of GDNF transcription. Finally, such results allow proposing these sporting dog breeds as natural models for clinical trials with a double benefit for human and veterinary medicine.

Indigenous Genomic Databases: Pragmatic Considerations and Cultural Contexts.

The potential to grow genomic knowledge and harness the subsequent clinical benefits has escalated the building of background variant databases (BVDs) for genetic diagnosis across the globe. Alongside the upsurge of this precision medicine, potential benefits have been highlighted for both rare genetic conditions and other diagnoses. However, with the ever-present "genomic divide," Indigenous peoples globally have valid concerns as they endure comparatively greater health disparities but stand to benefit the least from these novel scientific discoveries and progress in healthcare. The paucity of Indigenous healthcare providers and researchers in these fields contributes to this genomic divide both in access to, and availability of culturally safe, relevant and respectful healthcare using this genetic knowledge. The vital quest to provide equitable clinical research, and provision and use of genomic services and technologies provides a strong rationale for building BVDs for Indigenous peoples. Such tools would ground their representation and participation in accompanying genomic health research and benefit acquisition. We describe two, independent but highly similar initiatives-the "Silent Genomes" in Canada and the "Aotearoa Variome" in New Zealand-as exemplars that have had to address the aforementioned issues and work to create Indigenous BVDs with these populations. Taking into account the baseline inequities in genomic medicine for Indigenous populations and the ongoing challenges of implementing genomic research with Indigenous communities, we provide a rationale for multiple changes required that will assure communities represented in BVDs, as well as Indigenous researchers, that their participation will maximize benefits and minimize risk.