Amyotrophic Lateral Sclerosis (ALS) is a disease that damages motor neurons. These vital structures in the human body carry information between the brain and the rest of the body. They are also involved in automatic processes such as breathing, blood pressure and reflex actions.
ALS normally starts in a localized part of the body but gradually spreads. Someone who has recently been diagnosed may, for example, have difficulty doing up the buttons on their shirt or weakness in their legs.
ALS can be defined in different ways depending on its root cause and the clinical onset. As far as the underlying cause is concerned, the two different types are familial ALS and sporadic ALS.
When classifying the disease in terms of clinical onset, the two different terms used are spinal ALS and bulbar ALS.
Other forms of the disease are Guamanian ALS, which is more common in one location in the Pacific around the island of Guam, and Juvenile ALS which affects younger people.
Read on to learn more about each of the aforementioned types of ALS.
The most common type amyotrophic lateral sclerosis is sporadic ALS. In the USA, it accounts for over 90% of cases and essentially means that there is no genetic component that might have influenced the development of the disease.
Familial ALS accounts for the rest of diagnoses in the USA (between 5 and 10%) and it means there is a genetic influence at work. One or more family members have also had the disease and this has influenced the individual’s own diagnosis.
While there needs to be more work carried out in this area, the research suggests that if someone has the relevant gene there is a 50% risk of ALS being passed on to a child. The most common gene defect (accounting for as much as 40% of cases) is C9orf72 which holds the instruction for making a protein that is common in neurons.
Other genetic factors include ALS with an association to frontotemporal dementia. Another may be linked to Parkinson’s Disease.
Familial vs sporadic types of ALS are still the subject of much research. The common theory today is that many sporadic diagnoses might, in fact, have a genetic connection. A lot more work needs to be done in this area before we fully understand what is going on.
Another way of classifying ALS is how it presents in the clinical arena. There are two types here:
Types of amyotrophic lateral sclerosis can also vary because of where they occur and the age of the person they affect.
We still have much to learn about the different types of amyotrophic lateral sclerosis. While there may be more to a genetic component than was first thought, the vast majority of those affected are diagnosed with sporadic ALS.