A Natural History Study of Patients With GNE Myopathy and GNE-Related Diseases

Overview

Background: \- GNE Myopathy is a disease that causes walking difficulties and increasing muscle weakness. It usually develops in young adults (between 20 and 30 years of age), and affects arm and leg muscles. HIBM is caused by mutations in a gene that may affect how the muscles function. Researchers want to learn more about the causes, symptoms, and effects of HIBM. Objectives: \- To collect genetic and medical information from people with GNE Myopathy . Eligibility: \- Individuals between 18 and 80 years of age who have GNE Myopathy and do not use a wheelchair. - Participants must be willing to stop any current treatment of HIBM while enrolled in the study. Design: * Participants will be screened with a medical history, physical exam, and neurological exam. * At the first visit, participants will have the following tests: * Questionnaires about the impact of HIBM on daily activities, mood, and quality of life * 24-hour urine collection * Blood samples * Heart function tests * Muscle strength and endurance tests, including walking * Imaging study of the muscles * Participants will return for followup visits at 6, 12, and 18 months. They may be asked to return for a final visit at 24 months. Not all tests will be performed at each visit. * Treatment will not be provided as part of this protocol. For more information, visit our website: http://hibmstudy.nhgri.nih.gov/

This is a prospective observational study to evaluate patients with GNE myopathy and other GNE-related diseases. The GNE gene encodes for UDP-GlcNAc 2-epimerase/ManNAc kinase, the bifunctional enzyme that initiates and regulates intracellular sialic acid (Neu5Ac) biosynthesis and glycan sialylation. GNE myopathy is a rare, autosomal recessive myopathy with onset in early adulthood characterized by progressive skeletal muscle atrophy and weakness. The impairment of Neu5Ac production is presumed to cause decreased sialylation of muscle glycoproteins, resulting in muscle deterioration. Other GNE-related diseases such as congenital thrombocytopenia have been recently identified, but the pathophysiology is not well understood. In this protocol, we plan to evaluate patients with GNE myopathy and other GNE-related diseases clinically, biochemically, and molecularly to characterize the mechanisms of disease, to delineate the natural history, phenotypes, progression and complications of GNE-related diseases, and to identify endpoints and biomarkers to support clinical trials testing potential therapies.