164th ENMC International workshop: 6th workshop on centronuclear (myotubular) myopathies, 16–18th January 2009, Naarden, The Netherlands

Diagnostic approach to Paediatric and adult patients with myotubular/centronuclear myopathy (MTM/CNM). In neonates or infants with clinical and histopathological features of MTM/CNM (a), myotonic dystrophy must be appropriately excluded before further genetic testing is considered. Following exclusion of myotonic dystrophy, MTM1 mutation screening should be performed initially, particularly in males with a family history suggestive of X-linked inheritance, before other genes are considered based on clinical and histopathological findings. Identification of MTM1 mutations in females should prompt a search for associated X chromosomal abnormalities and/or skewed X-inactivation. In older patients with MTM/CNM (b), family history and/or the presence of certain clinical and histopathological findings may aid molecular genetic testing in some cases; however, none of these are invariable. Muscle MRI may be particularly useful in the DNM2- and RYR1-related forms where distinct patterns of selective muscle involvement have been reported . MTM1, myotubularin gene; DNM2, dynamin 2 gene; RYR1, skeletal muscle ryanodine receptor gene; BIN1, amphiphysin 2 gene; MHS, malignant hyperthermia susceptibility; CDH, congenital dislocation of the hips.