Exploiting Epigenome Editing in Kabuki Syndrome: a New Route Towards Gene Therapy for Rare Genetic Disorders

Overview

Starting from isolating primary cells from affected patients, an in vitro disease model system for KS will be developed. Using alternative strategies to obtain patient-derived mesenchymal stem cells, an integrative approach will be adopted for defining both the transcriptional and epigenetic regulatory networks perturbed upon the loss of function of KMT2D. Combining the self-renewal potential of mesenchymal stem cells (MSCs) with CRISPR/Cas9 technology, an epigenome editing approach as therapeutic strategy to rescue the activity of MLL4 will be developed. A step forward is expected towards the understanding of those the molecular mechanisms governing the aetiology of Kabuki Syndrome (KS) and that the proposed in vitro disease model will provide to the scientific community an experimental system to study the KS. Importantly, the aim is to define the molecular bases of KS and to develop a therapeutic strategy that could ameliorate some of the abnormalities associated with KS.

Main and secondary objectives : The main objective is to study the pathological role of ML mutations in KS to facilitate the identification and characterization of therapeutic strategies to improve the symptoms of patients with KS. Due to the lack of treatment in the KS, the aim is to develop a model of this disease from fibroblasts from patients and reprogram them into mesenchymal stem cells. This approach will generate a KS-specific stem cell bio-bank, allowing the identification of common disturbances caused by the loss of function (LoF) of KMT2D. The impact of the KMT2D LoF on transcription but also the epigenetic mechanisms activated during MSC differentiation will be described. Finally, the therapeutic potential of an epigenome "editing" approach to increase the expression of the wild KMT2D allele to restore the functional activity of MLL4 in treated MSCs will be evaluated. The secondary objective is to evaluate the ability to return to normal after CRISPR/Case9 gene therapy treatment on patients' cells Methodology (design study, population, description of groups (if applicable), inclusion criteria, non-inclusion, main and secondary judgment criteria, number of subjects to be included, statistical analysis...) : Starting from primary cells isolated from affected patients, an in vitro model of the disease will be developed. An integrative but alternative strategy approach to obtain mesenchymal stem cells derived from patients to define normal and abnormal transcription and epigenetic circuits during KMT2D LoF will be adopted. By combining the autonomous renewal potential of MSCs with CRISPR/Cas9 technology, an approach to "editing" the epigenome for therapeutic purposes to restore MLL4 activity will be developed. This project will represent a step forward in understanding the molecular mechanisms responsible for KS. The in vitro model will provide the scientific community with an experimental system to study KS. Finally, the aim is to define the molecular basis of KS and develop a therapeutic strategy to improve certain symptoms in patients with KS. Process (number of visits, duration of inclusions, duration of follow-up): 8 people will be included: 4 patients with Kabuki syndrome authenticated by the molecular genetics study of the KMT2D gene. 4 parents of the same sex as the patient Feasibility : In the clinical genetics department of the Montpellier University Hospital, more than 40 patients with Kabuki syndrome are followed. Impacts / prospects : The identification of the consequences of mutations in the KMT2D gene on epigenetic mark changes and cellular structural changes as well as the attempt at gene correction by CRISPR/Cas9 will provide a better understanding of the disease (and the genes that are deregulated by post-KMT2D epigenetic changes) and will also open a promising path for gene therapy by CRISPR/Cas9 method.