Clinical Research Directory

Muscle Health Measurements Using Electrical Impedance Myography

This study is being done to further develop a device, the mScan, to measure muscle health as compared to measurements of muscle health using MRI (magnetic resonance imaging). This device is held against the skin and uses Electrical Impedance Myography (EIM). EIM uses a very small, noninvasive (e.g. no needles), brief (about 6 seconds), and painless electrical current to measure the muscle. The investigators will look at how the mScan predicts the muscle measurements seen on MRI in people with and without muscle disease. The investigators hope that this can be used in the future as a quick, convenient and less time-consuming way than MRI to assess muscle health. This could be used to measure how well treatments for different muscle disorders are working over a period of time.

Transcriptomic Analysis to Put an End to Misdiagnosis in Patients With Rare Muscle Diseases

Since 2017, more than 250 analyses performed at the Molecular Genetics Laboratory of the Timone Enfant Hospital have yielded negative results in patients with rare genetic muscle diseases. The researchers hypothesise that some of these misdiagnosed patients carry pathogenic RNA (transcript) disrupting variants that were not identified by DNA sequencing. In fact, DNA sequencing analyses can be negative despite the presence of a pathogenic variant that disrupts RNA splicing or expression, causing a genetic disease. For this reason, RNA sequencing can provide a diagnosis in patients who have not been diagnosed by DNA sequencing, thus putting an end to diagnostic wandering. Thus, as a descriptive prevalence study, the objectives are first to determine the rate of positive diagnoses made by the RNAseq approach in patients with muscle diseases that have not yet been diagnosed, and then to identify the genomic characteristics of the pathogenic variants identified in patients by RNAseq analysis, in order to facilitate the identification of this type of variant in future patients. 50 patients will be included in this study during 2 years.

The Prevalence of RYR1-related Disease

The skeletal muscle ryanodine receptor (RYR1) gene encodes an important calcium channel in skeletal muscle, with an important role in muscle contraction. Mutations (i.e. disease-causing changes) in RYR1 are associated with an immensely wide range of clinical problems, ranging from inborn muscle conditions with profound weakness at birth ("congenital myopathies"), to a potentially fatal anaesthesia complication ("Malignant Hyperthermia, MH") in otherwise healthy individuals. Although RYR1-related conditions are believed to be amongst the most common neuromuscular disorders, their precise prevalence (i.e. the number of cases in a particular population at a given time) is currently unknown. Moreover, there is no information regarding the relative frequency of specific congenital myopathies, MH and related manifestations, such as the associated bleeding abnormality recently described by our team. The lack of reliable prevalence data represents a major obstacle to addressing the needs of individuals affected by RYR1-related conditions, to appropriate resource allocation, and to preparation for clinical studies ("trial-readiness") essential for therapy development. To address this shortcoming, we will conduct an international collaborative study involving neuromuscular and MH centres from the UK and the Netherlands, focusing on the prevalence of RYR1-related conditions, as a group and per subtype. The countries participating in this study were included because of 1) centralized RYR1 testing, 2) the presence of at least one database/registry with population-wide coverage capturing RYR1-related disorders and 3) of national myopathy and MH expertise centres. Information regarding RYR1-mutated individuals and their specific diagnosis will be obtained from national databases/registries, and analysed utilizing statistical methods that are well-established in the field of epidemiology. This study will provide important information regarding the actual disease burden of RYR1-related disorders on a wider scale, inform appropriate research resource allocation, and preparation for trial readiness. This study will be funded by the RYR1-Foundation.