Why aren't there any cures for genetic disorders?

Hm you guys should really give these questions more points but i'm always happy to help
Genetic diseases, such as Cystic Fibrosis and Huntington's disease, are caused by small differences in the DNA that we get from each of our parents. These differences affect how we use a particular gene, and that leads to disease. So we can't really get rid of a gene to cure a disease.

Because to recover the broken gene their is many risk for the human life and if we replace the gene with healthy and same function character but what is  the   guarantee  of human life may be the gene will work or not or if not then the death of the person may occur