When you learned about genes in high school, chances are it went something like this:

Our DNA holds about 20,000 protein-coding genes. To make a protein, a cell makes a copy of the corresponding gene, in the form of a single-stranded molecule called RNA. The cell uses the RNA molecule as a template to make the protein. And then the protein floats off to do its job.

That’s certainly true. But there’s more to the story.

Some of our genes don’t encode proteins; instead, they create long RNA molecules that don’t serve as protein templates. They have different jobs.

One of these so-called long-noncoding RNAs (lncRNAs, for short) is vital to women’s health. Women carry two copies of the X chromosome, of course, while men have only one. Yet both sexes produce the same number of proteins from X chromosomes. The cause of that balance is a lncRNA called Xist.

In each cell in a woman’s body, Xist locks onto one of the two X chromosomes and inactivates it. Then the cell is able to produce proteins only from the X chromosome free of Xist. If that bit of RNA fails, women produce extra proteins. Studies on mice suggest this can lead to cancer.