A Gene for Autoimmunity
Some years ago I bought stock in a company that investigated the genetic origins of disease. The company went bankrupt and I lost all my money, but there was nothing wrong with the research–just the business plan. Hope of finding a cure–for lupus and other diseases–may rest precisely in understanding the genetic basis of illness.
It was with this idea in mind that a study–A Comprehensive Analysis of Shared Loci between Systemic Lupus Erythematosus (SLE) and Sixteen Autoimmune Diseases Reveals Limited Genetic Overlap—was undertaken. As the title suggests, the study failed to produce evidence that there is a strong genetic link between people SLE and other autoimmune diseases. The authors of the study hypothesize that the correlation may be weak between SLE and many other autoimmune diseases because SLE is so “heterogenous”. That is, there are many ways in which SLE can manifest. Perhaps each manifestation of lupus has a different genetic association.
Interestingly (according to the authors), the strongest genetic association found was between SLE and rheumatoid arthritis. The authors hypothesize that maybe this strong link has something to do with the fact that the two diseases share a major symptom: arthritis. There was another, though weaker, genetic association found between SLE and scleroderma.
The authors also noted that several established genetic links to SLE were not found in other autoimmune diseases. The authors admit that the failure to find these links may be due to a problem with the study’s methodology and that future efforts may be able to detect these associations.
So where do I think this leaves us? Well, there doesn’t seem to be an autoimmune gene, one common cause for a multiplicity of autoimmune diseases. And what the study shows, what it reinforces, is the fact that SLE, even on the genetic level, is a very complicated disease. Systemic lupus is more like several diseases than one and its cure may ultimately involve solving many genetic riddles, not just a single puzzle.
I personally think SLE might be approached the way cancer is increasingly treated: though it falls under the rubric of oncology, cancer responds to a variety of very specific therapies that have been designed for different manifestations of the disease. Something like that may evolve (is already evolving to some extent) for lupus. Though there may not be one gene that causes SLE, there may be different places on the genetic map where a susceptibility for distinct forms of lupus exist. And, just as tailored treatments are developed for different cancers, targeted treatments may need to be developed for different kinds of lupus.
There was a time when certain cancers carried with them very high mortality rates. Some of these, like lymphoma, today have dramatically improved cure rates. The day will surely come when people with lupus will experience the same success. They then will be able to look forward to futures that include the prospect of a complete cure.