X chromosome

The cassette was inserted on the X-chromosome and reduced the mating success of males, resulting in reduced offspring.

It’s possible, though not confirmed, that some women have tetrachromatic vision — a 2010 study found that some 12 % of human females carry an X-chromosome linked color deficiency that gives them four rather than three types of cone — but that, at least for the most part, they don’t have a corresponding ability to see “four-dimensional color,” as the study puts it, perhaps because the type of cone isn’t the only factor in how many colors you can actually see.

Nature has devised a clever, if complicated, workaround called X-chromosome inactivation.

As the researchers discovered, X-chromosome inactivation can lead to autoimmune disorders, but other factors can also cause these disorders -- which is why men sometimes develop them.

X-chromosome inactivation is achieved courtesy of a molecule called Xist.