Most of the mutations have no effects whatsoever on the organisms but some can be dangerous. There are two types of mutations that cause harm to the organism's ability to survive:teratogen muations are the mutations that form inside the uterus when the fetus is still developing and can even kill it or cause severe malformations that lead to death in the early life. Carcinogen mutations are the ones that lead to the formation of neoplasms(masses of cells that divide uncontrollably, basicly cancer).