And the fuse chromosome, this abnormal chromosome, is called chromosome 1421. So when the individual, when the Zygote basically gains this particular chromosome here, that individual, the Zygote, still has 46 of these chromosomes. But the 14th one, this one, is abnormal because it contains this duplication, this duplicated portion of the gene. And that can also lead to the same symptoms of down syndrome. So there are two forms of down syndrome. The much more common case, the one that is affected by the age of that mother, is tricymi, 21.