Myotubular myopathy is a well-defined entity within the centronuclear myopathy 
subgroup of congenital myopathies. The authors present a patient with the most 
severe X-linked recessive type (XLMTM). A baby boy presented at birth with 
severe hypotonia, weak spontaneous movements, arthrogryposis, and respiratory 
insufficiency. Muscle biopsy showed features of myotubular myopathy. The 
diagnosis was confirmed and further specified by genetic analysis, revealing a 
novel frameshift mutation (1314-1315insT) of the myotubularin-coding MTM1 gene. 
This case underlines the importance of interdisciplinary analysis of congenital 
muscle diseases, including histomorphological and genetic investigations.