If down syndrome means having an extra chromisome, which is harmful, does that mean that 2 extra would be ok since they make a pair?

Answer 1

No. The job of your DNA is to provide a blueprint for protein synthesis in the body. Any deviation from the "normal" will result in abnormal synthesis and therefore problems with its expression. This is the basis for almost all of the genetic problems we have. 2 extra would be expressed in ways that we could not predict and may even not be suitable to sustain life

Answer 2

no do not mock people who struggle...it is unkind

Answer 3

No. Tetrasomy 21 also leads to Down syndrome.