If one considers the metaphor that pre-mRNA is a long sentence, Nilsen says, then nucleotides and splice sites are the words of the sentence. "Adding or deleting one word," he says, "can radically change the meaning of the sentence."

According to Joseph Nadeau, Ph.D. chair of the genetics department in the School of Medicine, the most important conclusion of Nilsen's research is that "it's context, not code that's important." He says the current assumption of biologists is that there are rules that govern biological phenomena like alternative splicing, and those rules are hidden in the DNA code. So as soon as we break the code, this assumption predicts, we will be able to control alternative splicing and start curing the genetic diseases it causes.

In Nilsen's view, the context—the changes in no more than two dozen nucleotides near a possible splice point—is part of the genetic code. His team's discovery means that the code is much more complicated than scientists ever anticipated, and that fact will likely delay the day scientists can begin to intervene in the code to cure genetic diseases.