When I did research for a Stanford Medicine magazine piece last year, I was amazed at the number of unsolved mysteries surrounding autoimmune disease. No one knows for sure what causes the body to start attacking itself, for example, or why so many more women than men get these diseases.
There's also been uncertainty about why one such disease, lupus, strikes people of African and Asian descent more often than Caucasians - but a team of researchers now think they've figured out that mystery. They found that a specific gene variant is strongly linked to an increased risk of lupus and that the variant also makes a person more resistant to malaria, which occurs in African and Asian regions of the world. As explained by Booster Shots:
That means the gene would be useful, and selected for, in areas of the world where malaria is rife. In those places, the downside of increased lupus risk would be far outweighed by the added protection against malaria.
And -- like a fossil -- the gene variant would persist in the DNA of people whose ancestors came from malaria regions, even when those people don't live with the threat of malaria...
The gene in this case (known as Fc gamma RIIB) is a receptor involved in the immune response, and so the finding makes sense -- a ramped up immune system would help fight infection but could also raise the risk for autoimmune conditions.
The study appears in the Proceedings of the National Academy of Sciences.
Previously: Learning about lupus