Centronuclear and myotubular myopathy (CNM and MTM) are rare inherited neuromuscular diseases of which there are three forms of inheritance:
The term myotubular myopathy is currently used to describe the x linked form of the condition while centronuclear myopathy is used to refer to the autosomal forms. Collectively, the three forms are known by the umbrella term of ‘centronuclear myopathies’ as illustrated below.
Mutations in a number of other genes namely CACNA1S, SPEG, ZAK, MTMR14 and MAP3K20 (ZAK) genes have recently been identified in patients with clinical features of a congenital myopathy and central nuclei on muscle biopsy, however, these patients are relatively rare. There are also a proportion of cases of centronuclear and myotubular myopathy for which the causal gene is unidentified, even though a diagnosis has been made by muscle biopsy.
The centronuclear myopathies belong to a group of conditions known as congenital myopathies which are inherited muscle disorders from birth. The characteristic feature of the centronuclear myopathies, is the presence of the nucleus in the centre of the muscle fibre instead of the usual position at the edge, manifesting as defects in the cell structure of voluntary muscles, causing low muscle tone and affecting children and adults at various stages of life. One of several different types of congenital myopathy, the word ‘myopathy’ is derived from the Greek language – the word ‘myo’ means muscle and the word ‘pathy’ means disease.
Centronuclear and myotubular myopathy are neurological conditions not cognitive conditions. Many affected children are trached, meaning that a tube is inserted into the individuals neck to help them breath and this may result in them being behind with their language skills but a speaking valve can help with this. Sadly, people are mistakenly led to believe that they have learning difficulties – but the brain is not a muscle and it is more usual that these children are exceptionally bright and intelligent for their years. Children can be taught sign language which helps them communicate until they are able to talk and a speech therapist can teach exercises that help strengthen the muscles in face and throat. Other forms of the condition present later in life and are considered to be milder, however, all forms of the condition can be managed.
The conditions are so rare that there are no good estimates of their incidence, a guess-timate would be somewhere between 1/50,000 and 1/100,000 for each form and perhaps slightly greater when the forms are combined. To put this into perspective, Duchenne Muscular Dystrophy affects about 1 / 3500 male births or 1 in 7000 children born (Source: The Beggs Laboratory).
Further information
Further information about centronuclear and myotubular myopathy can be found below.
Condition specific resources
UK and Europe
USA
Other resources
The Muscular Dystrophy Campaign have produced a factsheet about centronuclear and myotubular myopathy.
The American Society of Gene and Cell Therapy have produced a set of infographics and a short film describing what x-linked myotubular myopathy is and how gene therapy works.
The Big Sunflower Project 