Now, notice in this particular case I've discussed nondisjunction taking place during anaphase two of meiosis. But nondisjunction can also take place during anaphase one of meiosis. And in both cases we can basically produce a Zygote that contains trisomy 21. So trisomy 21 is the much more common case of down syndrome. Now, the other much less common form of down syndrome is translocation. Now, translocation, if you remember from our discussion on chromosomal abnormalities, translocation is the process by which a segment of a chromosome breaks off and moves onto and attaches onto a different non Homologous chromosome.