Zombie DNA

Less than half of our DNA codes for active genes. The rest is commonly called "junk", although I have always suspected that some of it does other things that we don't yet understand. Some bits of junk DNA seem to be inactive genes, or parts of them, inherited from our distant ancestors. The notion that some of them could come back to life and hijack our bodies has long interested science fiction writers, as in the Star Trek TNG episode where the crew all turns into various ancestral animals. And now science catches up, sort of:

The human genome is riddled with dead genes, fossils of a sort, dating back hundreds of thousands of years — the genome’s equivalent of an attic full of broken and useless junk.

Some of those genes, surprised geneticists reported Thursday, can rise from the dead like zombies, waking up to cause one of the most common forms of muscular dystrophy. This is the first time, geneticists say, that they have seen a dead gene come back to life and cause a disease. . . .

The disease, facioscapulohumeral muscular dystrophy, known as FSHD, is one of the most common forms of muscular dystrophy. It was known to be inherited in a simple pattern. But before this paper, published online Thursday in Science by a group of researchers, its cause was poorly understood.

The culprit gene is part of what has been called junk DNA, regions whose function, if any, is largely unknown. In this case, the dead genes had seemed permanently disabled. But, said Dr. Collins, “the first law of the genome is that anything that can go wrong, will.” David Housman, a geneticist at M.I.T., said scientists will now be looking for other diseases with similar causes, and they expect to find them.