MYOTONIC DYSTROPHY
Myotonic dystrophy is a long-term genetic disorder characterized by progressive muscle wasting and weakness.
- It is a part of a group of an inherited disorder called muscular dystrophy. It is the most common form of muscular dystrophy with onset in adulthood
- People who have this condition may be unable to relax their muscle at will following contractions or use.
- Muscles in the lower legs, hand, neck, and face are mostly affected and this may get worse over time.
- For example, a person may have difficulty releasing their grip on a doorknob, handle, or even after shaking hands with someone .
- The weakness and muscle wasting characterized by this condition can progress to the point of disability. Disability does not get severe until about 15 to 20 years after symptoms appear.
- It is also referred to as dystrophia myotonica (DM) or Steinert disease.
- The condition can occur at any age but signs and symptoms typically appear in early 20s 0r 30s.
CAUSES
Myotonic dystrophy is a genetic condition inherited in an autosomal dominant pattern.
The autosomal trait is one of the several ways that a trait disorder can be passed down through families
In an autosomal dominant disorder, only one copy of the defective gene is needed to be passed down from the parent before a person gets the disorder. Each child in the family, therefore, has a 50% chance of inheriting the gene that causes the disorder.
Two types of myotonic dystrophy exist based on the underlying genetic mutation: type 1 and type 2
In type 1, there is an abnormal expansion of a repeated region in the DMPK gene found in chromosome 19. A severe type of Type 1 is called the congenital myotonic which can be seen at birth. Congenital myotonic dystrophy has only be seen in Type 1 and not in the Type 2.
In type 2, there is an abnormal expansion of a repeated region in the CNBP gene found in chromosome 3.
The expansion of the DNA in these two genes appear to have many complex effects on the cellular process, preventing muscle cells and cells in other tissues from functioning normally. This leads to the symptoms of myotonic dystrophy
SYMPTOMS
Symptoms associated with Type 2 are usually milder and progress slower than those of Type 1 and vary greatly according to the age of the person with the disorder.
Symptoms may include:
- Difficulty swallowing
- Weight loss
- Irregularities in the electoral control of their heartbeat
- Cataracts (clouding of the lens in the eyes)
- Increased sweating
- Drooping muscle in the face, producing a thin and haggard facial structure
- In females, the muscles of the uterus can behave abnormally, leading difficulties in childbirth
- Premature balding is more common in men
- Difficulty lifting the heads due to weak neck muscles
- Muscle weakness in the feet which may make it easy to fall
In the congenital myotonic, the babies affected have weakness of all their muscles, breathing problems, and developmental delays including mental retardation. These medical conditions may be so severe and may cause death.
DIAGNOSIS AND TREATMENT
Diagnosis may be made through a physical examination or through presentation of symptoms. During the physical exam, the doctor will identify the pattern of muscle wasting and weakness.
Laboratory tests such as electromyography can be used to clarify the clinical diagnosis.
The definitive test is a genetic test. For this test, a blood sample is examined to identify the alterations in the gene within the chromosomes which are contained within the white blood cells.
TREATMENT
There is no cure for the condition.
When muscle weakness gets worse, ankle supports and braces can help.
Certain medication is also available that can lessen the muscle weakness.
Other symptoms such as heart and eye problems can also be treated