[From many - one.]

Down's is trisomy 21, in other words 3 instead of 2 of chromosome 21.

It's not a point mutation if that's what you were arguing about.

[jwalsh07]

Downs is a chromosomal mutation. Period.

[jwalsh07]

Down's is trisomy 21, in other words 3 instead of 2 of chromosome 21.

Sometimes, sometimes not. Always with nondysjunction. Partial trisomy does not affect every chromosome 21. Translocation does not result always result in trisomy but results in Downs, the extra #21 chromosome can attach elsewhere. Translocation is heritable.

It's not a point mutation if that's what you were arguing about.

Now you're on my side.