Amyotrophic lateral sclerosis or ALS is better known as Lou Gehrig’s disease and is a neurodegenerative disease that appears during midlife of an adult. It results in progressive motor neuron loss, making voluntary and eventually even involuntary movement impossible, eventually being fatal. The etiology or cause of ALS is not well understood although there is a focus on studying possible genes involved. This may not be the best approach because only 10% of individuals diagnosed with ALS is considered familial (or with heritable genetic origins) compared to the other 90% being sporadic. Sporadic ALS appears in an individual with no family history of the disease and is not necessarily linked to a heritable gene.
One gene that has been studied extensively (even though there isn’t a strong genetic connection to most ALS cases) is the SOD1 gene. SOD1 stands for superoxide dismutase 1 and is an enzyme (or molecule) in our cells that breaks down dangerous chemicals called reactive oxygen species (ROS) that can cause cells to age prematurely and eventually die. A mutation in the SOD1 gene causes the enzyme not to work properly which leads to an accumulation of ROS in the cell and may cause the cell to age and die from stress.
Mutations in the SOD1 gene are found in about 20% of familial ALS patients and 7% of sporadic ALS patients. Even though these numbers may seem small, they represent the largest percentage of individuals that have a similar mutation, which is why SOD1 is so widely studied. This certain mutation is also how scientists study ALS in animals. The animal model used has the mutant version of SOD1 and shows many of the symptoms of ALS.
This leads to the question: should those individuals diagnosed with ALS and their offspring be required to have genetic sequencing (testing) and counseling? Although ALS may not be consistently genetic, if it could identify even a few individuals who may have the disease early enough on to teach them about the disease before they have their own children it may be worthwhile. However, this broaches many ethical considerations. For example, what if an individual whose parent is diagnosed with ALS does not want to know if their genes are mutated? Is there an ethical responsibility on that individual if they have children even if they know they may be a “carrier” of ALS? Is there an ethical need for these individuals and any possible children to undergo genetic counseling to better understand and process their condition and possibility of fatal disease? Much of the considerations surrounding diseases as devastating as ALS turn out to be ethical, instead of medical, in the end. That is not to say however, that continuing supporting, funding, and doing research on ALS won’t help to elucidate the cause and find new treatments for the disease.
ALS: What’s the best approach when the answer is not in your genes?
