How can several different mutations cause the same genetic disease?

Several different mutations can cause the same genetic disease when we consider that t he actual position of the mutation in the gene may vary but still result in a defective gene. For example, there are many mutations that can lead to cystic fibrosis. We can count up to more than one thousand different mutations that can lead to the same sickness. If chromosomes are affected while they are developing you can expect genetic diseases.