We like to think that disease is simple. Medical researchers and molecular biologists know better, of course, but that rarely filters out into our broader cultural imagination. The popular press is filled with stories about toxins or disease-causing genes because we want simple answers to complicated questions. If there is a gene for cancer, then it’s easy to explain, right? The gene causes the cancer, just like a gene might give you blue eyes or red hair. Toxins are even simpler: if you get poison in your cells, they might die. Nothing could be easier to understand.
But the latest medical breakthrough concerning amyotrophic lateral sclerosis (ALS), a disease that gained attention in 2014 because of the publicity generated by the “ice bucket challenge,” can shed some light on the complicated relationships between genetics and disease.
ALS kills the nerve cells that control movement. Over time, muscles get weaker and waste away. It first became well-known in the United States when it affected baseball player Lou Gehrig, and as a result it is informally called Lou Gehrig’s Disease. Today, the most famous person living with the disease is physicist Stephen Hawking. It can start expressing itself as a simple weakness in the arms and legs, but can lead to loss of all motor skills.
ALS has confounded scientists and doctors for years. Research found a connection with genetics only in a small percentage of cases; most cases appeared randomly. Detailed cellular research has shown that a regulatory protein called TDP-43 is clumped in the nerve cells of ALS patients. This seemed important, but nobody knew whether this “clumping” was a cause or an effect of the disease, or how it might be related to the symptoms.
This is where the researchers at Johns Hopkins University came in. For the first time, they put together a coherent story about exactly what might be happening “behind the scenes”
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