Congenital myopathies are a group of conditions that affect the proximal – shoulder, upper arm, pelvic and thigh – muscles causing muscle weakness and wasting. Myotubular, or centronuclear myopathy, falls within this group. There are three main types of myotubular myopathy, each defined by the pattern of inheritance seen. Each of these is very rare.

Myotubular myopathy refers to the appearance of the affected muscle fibres that look like ‘myotubes’ which are muscle cells found only during foetal development. The condition is also sometimes known as ‘centronuclear myopathy’ because the nuclei of affected muscle cells are found in the centre of the cell instead of around the edge (which is what happens in healthy muscle cells).

There are different three forms of myotubular myopathy. The most severe form presents antenatally or at birth, and is the most common. Symptoms include a lack of foetal movement in the late stages of pregnancy, and swallowing and breathing difficulties at birth. In extremely severe cases the baby may not survive more than a few days. This type of myotubular myopathy is inherited in an X-linked pattern.

The other two forms, automomal dominant and autosomal recessive, are very rare and present later in life with milder symptoms. These include:

  • paralysis of the muscles of the eye
  • drooping eyelids
  • facial weakness
  • enlargement (hypertrophy) of the calves

Sporadic cases have also been reported where there is no previous family history.

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