Chi non ha ereditato la mutazione, non la trasmette?

Hi, I wanted to know if a child has a 50% chance of inheriting the gene of the disease, it means that if he or she has not inherited it is a healthy person and so will not transmit it?

Exactly: if the child of an affected parent has NOT inherited the mutation, he or she will NOT pass it on to the next generations. Huntington's Disease does not skip generations.