Skin Degeneration Ethical Dilemma - SERIOUS Answers Only!?

Ethical Dilemma - SERIOUS answers only!? - skin degeneration

This should be an argument of ethics. Set aside religious beliefs and personal values. If you do not answer do not understand dillemmas ethical reasons.

A child is born with a rare virus that causes skin, muscle and organ degeneration. The maximum life expectancy of no longer than 3 years.

The baby's vital signs, body movements and constant crying, it is clearly in pain and your body is under great pressure.

Under the assumption that active euthanasia is legal, and assuming that it is the parents' desire to end suffering for the child until the end of his life ...

1) Why is it ethically wrong for doctors to give the child a lethal injection? Or why it is ethically acceptable?

2) Is it ethical to hasten to deny life-sustaining treatment to death if he agrees that the situation will eventually kill them? For example, do not put on a ventilator, if I can not breathe alone? Why or why not?