The disorder
MYOTONIC DYSTROPHY
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
1.
Difficulty to solve problems
Emotional and behavioral changes
Daytime somnolence
Damage in peripheral nervous system
2.
Lower number of antibodies in blood
3.
Breathing problems in newborns
Pulmonary infections
Inhalation of food/fluids in respiratory system
Inability to breathe in sufficient oxygen
Sleep apnea
4.
Problems in pregnancy and giving birth
Complications with newborns
5.
Muscle weakness (Myopathy)
Rigid muscles and difficulty in relaxing muscles (myotonia)
Muscle wasting
Severe muscle weakness and delayed development in newborns
6.
Cataracts
Damage in the retina
Drooping eyelids
7.
Cardiac problems (arrhythmia)
Enlarged heart muscle
Low blood pressure
Sudden death
8.
Difficulty on swallowing
Gallstones
Enlarged colon
Constipation, diarrhea, irritable bowel syndrome, intestinal reflux
9.
High risk of sustaining a benign skin tumour (pilomatrixoma)