About

Centronuclear (and myotubular) myopathy are rare inherited neuromuscular diseases of which there are three forms, x-linked, autosomal dominant and autosomal recessive.

The conditions manifest themselves as defects in the cell structure of voluntary muscles, causing low muscle tone and affecting children and adults at various stages in life.

Centronuclear and myotubular myopathy are 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.

Congenital Myopathies 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.

The term centronuclear myopathy is used to refer to the two autosomal forms of the condition, whilst the term myotubular myopathy is used to describe the x linked form of the condition. Collectively, the three forms are known as the centronuclear myopathies.

The centronuclear myopathies 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.

Characteristics:

X Linked Myotubular Myopathy

Although all forms of centronuclear myopathy are considered rare, the most commonly known is x-linked myotubular myopathy which it is estimated affects 1 in 50,000 males from birth. There are also incidences of female x-linked manifesting carriers. Those affected by x-linked myotubular myopathy often have diminished respiratory capacity and are often partially or totally ventilator dependent. Parents are frequently told their children will not live past their first birthday but this is untrue. Many of the children with this condition 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.

Dominant Centronuclear Myopathy

The Autosomal Dominant form of Centronuclear Myopathy is generally not as severe as the x-linked or recessive forms of the condition and follows a mild course. It has been noted that the condition can affect individuals differently with onset ranging from birth to 50 years. Many are often able to walk well into adulthood but do find themselves in a wheelchair in later life, however the age that this occurs is not consistent among those affected. Those with the condition often report deterioration in their ability to carry out everyday tasks such as walking up stairs, rising from a sitting position unaided, lifting and carrying and with tasks such as opening bottles.

Recessive Centronuclear Myopathy

The Autosomal Recessive form of centronuclear myopathy usually occurs in infancy or early childhood. Weakness of the muscles in the face may occur, as may droopiness of the eyelids. Some people may have problems with feeding. There is usually weakness of the muscles closest to the trunk of the body, known as the proximal muscles.