When these early cells divide, each passes on its X inactivation.

当这些早分裂时，每个都会传递其 X 失活。

The embryo split into twins before X inactivation, so each twin ended up with a different inactivation pattern.

胚胎在 X 失活前分裂成双胎，因此每对双胎最终都有不同的失活模式。

Women with one mutated gene copy have a remaining healthy copy, so they don't get hemophilia unless X-chromosome inactivation turns off the normal copy in the majority of cells.

携一个突变基因的女性还有一个健康的基因，所以她们一般不会患血友病，除非X染色体失活使得大多数中正常的基因默。

There are still unresolved questions about X inactivation, like how some genes on the X chromosome escape inactivation and why inactivation isn't always random.

关于 X 失活仍有未解决的问题，例如 X 染色体上的一些基因如何逃脱失活以及为什么失活并不总是随机的。

Now if this inactivation's random, you'd expect about half of the female's cells to have a functional dystrophin gene and the other half to have a defective dystrophin gene, and these people are typically asymptomatic.

如果失活是随机的，可以预料到女性一半的中抗肌萎缩蛋白基因是正常的，另一半是有缺陷的，通常这些人无临床症状。