A natural history study in Limb Girdle Muscular Dystrophy 2I : magnetic resonance imaging, spectroscopy and physical outcome measures

Abstract

Limb Girdle Muscular Dystrophy 2I (LGMD2I) is caused by mutations in the fukutin related protein gene (FKRP). It is an important and frequent cause of LGMD, particularly in Northern Europe, and can range from a severe muscular dystrophy in childhood, very similar to Duchenne muscular dystrophy, to a much milder adult disease. Respiratory involvement and cardiomyopathy are common. This thesis aims to assess the natural history of a particular subset of this rare condition across four main European centres. Thirty eight ambulant LGMD2I patients from Newcastle, London, Paris and Copenhagen were recruited. The age range was 18-64 years and disease duration, 0-49 years. Magnetic resonance imaging (MRI) and Magnetic resonance spectroscopy (MRS) have both been performed. T1-weighted images were used to assess fat infiltration patterns using a qualitative radiological score and a quantitative 3-point Dixon technique, applied over two time points, and was performed to track the progression of fat infiltration. MRI fat infiltration has been correlated with muscle strength and function longitudinally. In the Newcastle upon Tyne cohort, cardiac MRI was also studied assessing the cardiac involvement in this condition. Chapter 1 presents an overview of muscular dystrophy and the current knowledge in LGMD2I and chapter 2 includes a literature review of both skeletal muscle and cardiac imaging. Chapter 3 focuses on the methodology of the study, including the patient demographics, physical assessment tools and MRI and MRS specifics. Chapters 4 -9 contain the results section; including physical and functional assessments, both cross-sectional and longitudinal, the cross sectional and longitudinal MRI results, skeletal MRS, cardiac MRI data and the FKRP registry respectively. Discussion of the results is found at the end of each chapter. Chapter 10 concludes with areas for future research.