News about research in Charcot-Marie-Tooth disease, congenital myasthenic syndromes, Duchenne/Becker MDs, Friedreich's ataxia, Pompe disease and spinal-bulbar muscular atrophy
Researchers supported in part by MDA have developed flow charts to guide genetic testing for the various subtypes of Charcot-Marie-Tooth disease (CMT), streamlining the testing procedure and reducing its cost. Currently, many patients undergo testing for a large number of CMT-causing genetic mutations through very expensive CMT "panels." The new flow diagrams guide physicians on which tests to order by taking into account clinical information, such as the speed and strength of nerve signals in the patient, the disease history and the family inheritance pattern. Read the whole paper and an accompanying editorial without charge at Charcot-Marie-Tooth disease subtypes and genetic testing strategies and The death panel for Charcot-Marie-Tooth panels, respectively.
Scientists supported in part by MDA have identified mutations in the gene for the plectin protein as a rare cause of a congenital myasthenic syndrome (CMS). Congenital myasthenic syndromes are caused by a number of different genetic mutations, all of which affect signaling at the neuromuscular junction, where nerve and muscle fibers meet. See Myasthenic syndrome caused by plectinopathy.
Pharmaceutical companies GlaxoSmithKline and Prosensa announced Jan. 19, 2011, that the first patient had begun treatment in a phase 3 study to test GSK2402968, a drug designed to coax muscle cells to ignore (skip) genetic instructions in the exon 51 region of the dystrophin gene. This experimental drug is a potential treatment for Duchenne muscular dystrophy (DMD). It's been estimated that up to 13 percent of those with DMD may benefit from skipping exon 51. The trial is designed to enroll 180 patients from up to 18 countries. There are no sites open in the United States at this time.
See GSK and Prosensa Announce Start of Phase III Study of Investigational Duchenne Muscular Dystrophy Medication and A Clinical Study to Assess the Efficacy and Safety of GSK2402968 in Subjects with Duchenne Muscular Dystrophy.
A phase 2 study of this drug is under way in Europe (see Phase II Double-Blind Exploratory Study if GSK2402968 in Ambulant Subjects with DMD), and a phase 1 study is under way in Columbus, Ohio (see Double-Blind, Escalating-Dose, Randomized, Placebo-Controlled Study Assessing PK, Safety and Tolerability of GSK2402968 in Nonambulant DMD Subjects.
Investigators have found that noninvasive magnetic resonance imaging (MRI) of DMD-affected muscles has potential as a tool to evaluate muscle preservation in this disease. See Muscle histology vs MRI in Duchenne muscular dystrophy.
Investigators in Australia supported in part by MDA have developed a new technique that they describe as "simple and rapid" for determining the presence of interruptions in the expanded section of DNA in the frataxin gene that causes Friedreich's ataxia (FA). There is evidence that such interruptions lessen the severity of the disease course. See the entire paper for free at Detection of interruptions in the GAA trinucleotide repeat expansion in the FXN gene of Friedreich ataxia.
Amicus Therapeutics plans to conduct a small trial of its experimental compound AT2220 in conjunction with enzyme replacement therapy in patients with Pompe disease during the first half of 2011. AT2220 is designed to stick to and increase the stability of a protein, such as the enzyme needed in Pompe disease. See Amicus Therapeutics Provices 2011 Business Outlook and Expected Key Milestones.
Dutasteride (Avodart), a drug that reduces testosterone activity, did not significantly slow the progression of muscle weakness in men with spinal-bulbar muscular atrophy (SBMA) in a two-year trial in which 50 men with SBMA were randomly assigned to take the drug or a placebo. However, there were fewer people in the dutasteride group reporting falls than there were in the placebo group, and there were some indications of both positive and negative effects of the drug compared to a placebo. See Efficacy and safety of dutasteride in patients with spinal and bulbar muscular atrophy: a randomised placebo-controlled trial; Dutasteride for spinal and bulbar muscular atrophy; and Dutasteride to Treat Spinal and Bulbar Muscular Atrophy (SBMA).
Editor's note 2/23/11: This article was updated 2/23/11 to correct the link to the paper about detecting interruptions in the frataxin gene.