Clinical features in X-linked myotubular myopathy carriers

Objective: To characterize the spectrum of clinical features in a cohort of X-linked myotubular myopathy (XL-MTM) carriers, including prevalence, genetic features, clinical symptoms and signs, as well as associated disease burden. Methods: We performed a cross-sectional online questionnaire study among XL-MTM carriers. Participants were recruited from patient associations, medical centers and registries in the United Kingdom, Germany and the Netherlands. We used a custom-made questionnaire, the Checklist Individual Strength (CIS), the Frenchay Activities Index (FAI), the SF-12 Health survey and the McGill Pain Questionnaire (MPQ). Carriers were classified as manifesting or non-manifesting, based on self-reported ambulation and muscle weakness. Results: The prevalence of manifesting carriers in this study population (n=76) was 51%, subdivided into mild (independent ambulation, 39%), moderate (assisted ambulation, 9%) and severe (wheelchair-dependent, 3%) phenotypes. In addition to ...