Causes, Types and Testing For Myotonic Dystrophy

Submitted on March 27, 2012

Myotonic Dystrophy is a genetic disease that is passed on from one generation to the next. If a person is suffering from myotonic dystrophy, at least one of the offspring could contract the disease. It is very likely that the offspring suffers from the symptoms of the disease. However, it is extremely difficult to diagnose this disease since the symptoms vary greatly from person to person. Some patients show very mild symptoms, while others experience them severely.

This is an extremely rare disease with very low incidence. It is estimated that the incidence is as low as 1 person in every 8000 persons. A congenital defect has even lower incidence, with only about 1 in 100,000 people suffering from the genetically acquired disease right from birth. Since the incidence is so low, many times even the most qualified doctors are unable to diagnose it correctly. Due to this organizations like the International Myotonic Dystrophy Organization have been set up. This organization assists people who suffer from myotonic dystrophy.

Types of Myotonic Dystrophy

There are two types of myotonic dystrophy - Myotonic Dystrophy Type I and Myotonic Dystrophy Type II. Type I of this disease can be divided into four distinct types according to the period of onset of the disease. The first is the most common, a congenital form of the disease. The second one is a juvenile type in which the onset is in the teenage. The third is the adult type in which it begins between the ages of 20 and 40. The fourth type is a mild myotonic dystrophy that could occur after the age of 40.

Causes for Myotonic Dystrophy

Though the cause of myotonic dystrophy is not completely known, it is suspected that the disease occurs due to repeated CTG attacks on chromosome number 19. The disease progressively gets worse, and therefore, there is a window period of anticipation in the disease. Genetic testing for myotonic dystrophy is conducted to find out if it is present in a child. It has been observed that about 50% of the children born to a person with myotonic dystrophy inherit the disease.

A monotonic dystrophy test can only detect abnormal genetic material. Unfortunately, testing for myotonic dystrophy cannot predict the onset of the disease. Most of the time, the disease only affects one essential system of the body. It usually strikes the optic system, heart, and muscles. However, since biochemical reactions may have a universal effect, the disease may cause some other problems too.