PKU, phenylketonuria, is a disease caused by a recessive gene. Two recessive genes must be present in order for the disease to occur.

answer; ///the above statement is (true);

increases the risk of extinction 

explanation:

the answer is that if the species suffers from the disease, there is nothing stronger than the others, so it is possible to remove wholeness. an example of this is hunger in irish potatoes, which has a deadly disease bearish part of all potato harvest masses. pretty much ruins the land of crops.