The disorder


Myotonic Dystrophy (MD) is a kind of muscular dystrophy that affects both muscles and other organs in the body. MD is a rare disorder that affects 1 in 8000 people worldwide and can be of two main types depending on the genetic disorder that causes the condition.

Of the two types of disorder, the type 1 myotonic distrophy (MD1 or Steinhert Disease,OMIM: 160900) is the most common. MD1 is a disorder of a dominant autosomal pattern caused by an unstable trinucleotide expansion of the 19q13.3. chromosome. Excellent reviews can be found on the genetic origin of  DM1 and the role of toxic RNA in this pathogenesis.

The expansion (CTG) n responsible for DM1 may vary from 50 to more than 1000 repeats and contributes to a wide range of different phenotypes.

According to the Myotonic Dystrophy Consortium (IDMC) (Neurology,2000) there are 3 recognized types of clinical phenotypes in MD1 depending on the age at the time of the onset and the repeats (CTG) n:


Mild: 50- 150 repeats CTG

Standard (adults) late onset: 100-1000 repeats

Congenital: More than 1000 repeats


Clinically MD1 is characterized by progressive muscle wasting and weakness, myocardiopathy , resistance to insulin and cataracts, among others. MD1 equally affects men and women



At present there is no known cure for patients with MD1, only palliative treatment for the symptoms, and therefore the existence of multiple medical needs of this group of patients which are not being covered

MD1: A multisystem disorder



Difficulty to solve problems

Emotional and behavioral changes

Daytime somnolence

Damage in peripheral nervous system



Lower number of antibodies in blood



Breathing problems in newborns

Pulmonary infections

Inhalation of food/fluids in respiratory system

Inability to breathe in sufficient oxygen

Sleep apnea



Problems in pregnancy and giving birth

Complications with newborns



Muscle weakness (Myopathy)

Rigid muscles and difficulty in relaxing muscles (myotonia)

Muscle wasting

Severe muscle weakness and delayed development in newborns




Damage in the retina

Drooping eyelids



Cardiac problems (arrhythmia)

Enlarged heart muscle

Low blood pressure

Sudden death



Difficulty on swallowing


Enlarged colon

Constipation, diarrhea, irritable bowel syndrome, intestinal reflux



High risk of sustaining a benign skin tumour (pilomatrixoma)