Genetic research into the cause of ALS

Is ALS Genetic?

Amyotrophic lateral sclerosis (ALS) is a degenerative disease that destroys neurons in the body. It’s a chronic condition that gets gradually worse over time as it progresses.

ALS affects around 30,000 people in the US alone and about 5,000 are diagnosed with it every year. Symptoms include loss of movement and mobility, speech problems and trouble eating as well as breathing issues. There is no cure for this disease and it is eventually fatal.

Research into ALS has been going on for a number of years and there have been some interesting breakthroughs. One of the most important areas of research is whether there is a genetic component to the disease and what this means for individuals who have been diagnosed with ALS.

Here we take a closer look at the difference between familial and sporadic ALS. While the evidence isn’t 100% clear, it does seem that there is a significant connection.

Is ALS Hereditary?

  • Familial ALS is where there is a genetic component. This means there is a gene that predisposes a person to the disease which is handed down from an ancestor who may have also suffered from it.
  • Sporadic ALS basically covers every other form of the disease. It simply means there is no genetic component and ALS can occur for a variety of reasons.

Research in the past showed that around 5 to 10% of ALS cases were familial. One of the problems with connecting the dots when it comes to familial ALS is getting information from the ancestral gene pool.

Someone who may have had a gene for the disease might have died before they were able to develop it, for example. In addition, our knowledge of genes is still being developed and there is much more to understand, especially when in comes to diseases.

There are more than 30 different genes that have been associated with ALS. That doesn’t mean having one of these in your DNA will increase your likelihood of contracting the disease. A defined connection can be something as simple as a gene being more prevalent in someone with the condition without actually affecting the outcome.

Recent research, however, may show that familial ALS is more common than we think. In fact, it could be that cases identified as sporadic ALS may have a genetic component.

Familial ALS

Woman having a saliva sample taken to test for ALS
A saliva sample being taken

Familial ALS vs sporadic ALS theories have been around for a while. New research is certainly beginning to change how we think about this disease.

Research published in 2017 in the online issue of Neurology found that, rather than 10%, it was more likely that 17% of ALS cases had a genetic component.

This study looked at 87 people who had been diagnosed with ALS. What they discovered was that rare gene variants associated with ALS were found in 25% of the patients. This was compared to 324 people who did not have the disease. In these, the rare genes were found in 15%.

This is backed up by research conducted at the University of St Louis in 2014, which found a significant genetic link in patients who had no previous family history of the disease. Results of the study found that 15 patients had a mutation of two or more ALS associated genes and 9 of these had no familial background.

While the samples are small in both these pieces of research, there is reason to suggest that the difference between familial ALS vs sporadic ALS is not as clear cut as we think.

Diagnosis of familial ALS usually involves investigating family history and looking at the disease symptoms. People with familial ALS often show their symptoms earlier than sporadic cases, for example.

With improvements in gene testing and gene therapy, there may be a road ahead that will lead to finding solutions for ALS. These are, of course, very early days. Test results (from blood and spit normally) are not always conclusive and can be difficult to interpret, even with today’s modern technology.

Those who are aware of familial ALS and who want to get themselves tested to see if they have the ‘wrong’ genes need to be a little wary that results could be inconclusive.

Ongoing Research

While there remains a lot of work to be done in this area, the research into familial ALS is proving promising. What initially seemed like a relatively small pool of individuals might indeed be much larger. Research continues with the aim of gaining a greater understanding of the condition and possibly one day finding a cure.