It was always a good bet that all the so-called junk DNA in our genomes wasn’t nonfunctional trash. Gradually functions are being found for some of it. Now comes word, via Science Online, that a form of muscular dystrophy is caused by a supposedly dead gene in the junk mutating into an active form.
It causes progressive weakening of muscles in the forearms, shoulders and face. It is a dominant trait with a 50-50 chance of being inherited by children of those with the disease. It afflicts about 1 in 20,000 people.
From the new finding, we now know that the gene that causes it is in all our genomes but normally disabled by the lack of something known as a poly (A) tail. This is a stretch of repeated adenine bases needed for any gene’s messenger RNA to get out of the nucleus and be translated into a protein. In this case, the defunct gene somehow has reacquired the ability to have the “tail” attached to its messenger RNA.
It’s a fascinating discovery, and the New York Times put Gina Kolata’s very good story on A1. She backs into the news, much as this post does, writing of fossil genes that “rise from the dead like zombies.” The Boston Globe picked up her story but rewrote the top with a straight lede that gets right to naming the disease in question. Over at Vanity Fair’s Web site, Alexandria Symonds needlessly whips up anxiety with a lede that says the finding is “something new and terrifying to worry about.” Symonds appears to have done no reporting herself, relying purely on Kolata’s story.
Kolata’s article provides some nice insight into the work. Science has so many great stories and it is nice to see some good writers using them. The idea that ‘dead’ genes could become reactivated is a compelling one.
Life and disease are so magically complicated, yet so wonderfully simple. Understanding the simple cause of a disease explains so many complex ramifications.
Of course, science, while often generating simplicity, always seems to generate more complex questions. This disease is only seen in people with less than 10 repeated copies of the gene and where some copies have become active.
What was the original purpose of the gene to begin with? At one time there must have been only one copy and it was active. What did it do and why has it become something deleterious unless inactivated?
I imagine some fun research will go into figuring it all out.