Sickle cell disease (SCD) is one of the most prevalent monogenic diseases in Europe. A single amino acid substitution in the beta-globin chain of the adult hemoglobin (Hb) drives red blood cell sickling and multi-organ damage. The clinical severity of SCD is alleviated by the co-inheritance of mutations causing expression of fetal gamma-globin in adult life ? a condition termed hereditary persistence of fetal hemoglobin (HPFH). Transplantation of autologous, genetically modified hematopoietic stem/progenitor cells (HSPCs) is an attractive therapeutic option for SCD patients. To this end, genome editing approaches based on the use of site-specific nucleases or, more recently, base editors have been explored by many groups, including teams in our consortium. These approaches either correct the single point mutation causing SCD or reactivate fetal gamma-globin expression by mimicking HPFH mutations. On the other hand, (pre)clinical data from SCD patients or SCD mouse models, as well as preliminary data from our labs suggest that SCD HSPCs are characterized by a high mutational burden, oxidative stress and expression of inflammatory genes. This can alter HSPC properties as well as their interactions within the bone marrow niche. In the context of gene therapy, it is essential to understand the mechanisms underlying SCD HSPC dysfunction and assess the impact of genome editing approaches on SCD HSPCs. In this proposal, we have assembled a multidisciplinary team to: (i) understand the molecular and cellular mechanisms underlying SCD HSPC autonomous and non-cell-autonomous dysfunctions and (ii) evaluate the impact of established and novel genome editing approaches on SCD HSPC properties and genome integrity. This study will lay the foundation of an improved gene therapy strategy to treat SCD and provide best practice tools and protocols for genome editing-based therapies in HSPCs.

Ciliopathies are a large group of rare and severe genetic diseases caused by dysfunction of the primary cilium, a microtubule-based cell surface antenna that controls key signaling output required during development and tissue homeostasis. Cilium dysfunction leads to complex disorders with high genetic heterogeneity and overlapping phenotypes. Despite the broad clinical spectrum, chronic kidney disease (CKD) leading to end stage kidney disease (ESKD) is a common cause of morbidity across ciliopathies. Currently, the only available standard of care for CKD is based on dialysis and transplantation. Renal ciliopathies represent a main cause of ESKD during childhood and despite the identification of more than 40 causative genes, it remains difficult to predict the severity of the disease as well as the risk of appearance (if not present at diagnosis) and the rate of progression of renal failure. TheRaCil therefore aims: (1) to improve diagnosis and prognosis of at risk pediatric renal ciliopathy patients, and (2) to implement therapeutic approaches aimed at targeting shared pathological pathways, at modifying mRNA targets of the causative or modifier genes by antisense oligonucleotides and by the repurposing of available molecules. These goals will be achieved through the federation of our unique databases of pediatric renal ciliopathies cases available across Europe, which will allow a better stratification of patients, the identification of modifier genes and markers of disease progression. Bioinformatics approaches will be used to integrate patients’ biological and genetic data as well as multi-omics and functional analyses from patients samples and preclinical models. These analyses should lead to the identification of shared targetable pathological pathways as well as of patients eligible for the identified new therapeutic approaches which will be evaluated in robust preclinical models.

As recognized by the Council Recommendation 2009/C 151/02, rare diseases (RD) are a prime example of a research area that can strongly profit from coordination on a European and international scale. RD research should be improved to overcome fragmentation, leading to efficacious use of data and resources, faster scientific progress and competitiveness, and most importantly to decrease unnecessary hardship and prolonged suffering of RD patients. In the specific context of the massive generation, need for reuse and efficient interpretation of data, introduction of omics into care practice and the structuration of RD care centers in European Reference Networks, it appears crucial and timely to maximize the potential of already funded tools and programmes by supporting them further, scaling up, linking, and most importantly, adapting them to the needs of end-users through implementation tests in real settings. Such a concerted effort is necessary to develop a sustainable ecosystem allowing a virtuous circle between RD care, research and medical innovation. To achieve this goal, the European Joint Programme on RD (EJP RD) has two major objectives: (i) To improve the integration, the efficacy, the production and the social impact of research on RD through the development, demonstration and promotion of Europe/world-wide sharing of research and clinical data, materials, processes, knowledge and know-how; (ii) To implement and further develop an efficient model of financial support for all types of research on RD (fundamental, clinical, epidemiological, social, economic, health service) coupled with accelerated exploitation of research results for benefit of patients. To this end, the EJP RD actions will be organized within four major Pillars assisted by the central coordination: (P1): Funding of research; (P2): Coordinated access to data and services; (P3) Capacity building; (P4): Accelerated translation of research projects and improvement outcomes of clinical studies.

Mendelian susceptibility to mycobacterial disease (MSMD) is characterized by severe infections with weakly virulent mycobacteria in otherwise healthy patients. All known 31 genetic etiologies are inborn errors of interferon gamma (IFN-g) immunity and collectively account for about half of the cases. We discovered private, hemizygous, predicted loss- of-function (pLOF) mutations in the X-linked ribosome recycling and reinitiation factor MCTS1 gene in five unrelated MSMD male patients. The connection with MSMD is surprising, because the MCTS1 protein is typically thought to be involved in housekeeping of translation machinery and translational control of gene expression. Although the genetic evidence alone is compelling, we propose to further prove causality by discovering the molecular and cellular mechanism by which MCTS1 deficiency underlies MSMD. This project will hence help to better understand the previously unappreciated connection between regulation of translation reinitiation and IFN-g immunity. The Casanova Group has worked on MSMD for more than 25 years and identified most inborn errors of IFN-g immunity. I have spent my PhD working on the basic molecular mechanism of MCTS1. I am therefore a highly suitable candidate to join the Casanova group and to work on this project.

Sickle cell disease (SCD) is one of the most prevalent monogenic diseases in Europe. A single amino acid substitution in the beta-globin chain of the adult hemoglobin (Hb) drives red blood cell sickling and multi-organ damage. The clinical severity of SCD is alleviated by the co-inheritance of mutations causing expression of fetal gamma-globin in adult life ? a condition termed hereditary persistence of fetal hemoglobin (HPFH). Transplantation of autologous, genetically modified hematopoietic stem/progenitor cells (HSPCs) is an attractive therapeutic option for SCD patients. To this end, genome editing approaches based on the use of site-specific nucleases or, more recently, base editors have been explored by many groups, including teams in our consortium. These approaches either correct the single point mutation causing SCD or reactivate fetal gamma-globin expression by mimicking HPFH mutations. On the other hand, (pre)clinical data from SCD patients or SCD mouse models, as well as preliminary data from our labs suggest that SCD HSPCs are characterized by a high mutational burden, oxidative stress and expression of inflammatory genes. This can alter HSPC properties as well as their interactions within the bone marrow niche. In the context of gene therapy, it is essential to understand the mechanisms underlying SCD HSPC dysfunction and assess the impact of genome editing approaches on SCD HSPCs. In this proposal, we have assembled a multidisciplinary team to: (i) understand the molecular and cellular mechanisms underlying SCD HSPC autonomous and non-cell-autonomous dysfunctions and (ii) evaluate the impact of established and novel genome editing approaches on SCD HSPC properties and genome integrity. This study will lay the foundation of an improved gene therapy strategy to treat SCD and provide best practice tools and protocols for genome editing-based therapies in HSPCs.