Variations in Myotonic Dystrophy

It is important to remember that Myotonic Dystrophy is a highly variable condition so it is difficult to predict how one individual will be affected.

The range of symptoms and severity of symptoms both vary enormously. Age at onset when the condition first appears can range from birth to old age. Although the disease is highly variable it can be broadly grouped into four categories, based on severity.

Age of onset

Minimal symptoms
Individuals develop symptoms late in life. Cataracts can be the only symptom or there may also be mild muscle involvement.

Classical or adult onset
This begins in adult life and is characterised by muscle stiffness and slowly progressive muscle weakness. Other systems are commonly involved but to varying degrees. This is the most common type of DM1 seen.

Childhood onset
This begins during childhood, but with no problems at birth. Like adult onset it can cause muscle weakness and stiffness, but sometimes it can also cause learning difficulties, glue ear and eye problems.

Congenital Myotonic Dystrophy
This is the most severe form of the condition and is present from birth. Babies with this can be quite ill, with breathing and swallowing difficulties around the time of birth. As they grow up children born with it have fewer problems with muscle weakness than adults initially, but they can often have problems with learning difficulties, glue ear, communication and behavioural problems. They then tend to develop similar problems to adults affected with “classical DM” but at a younger age.