It hasn't happened, in part because the methods for delivering copies of healthy genes to unhealthy cells were too crude, and in part because the most common human diseases do not have clear - cut genetic targets. (discovermagazine.com)
Examples of common human diseases caused by viruses include the common cold, the flu, chickenpox and cold sores. (sciencedaily.com)
Aneuploidy is known to be deleterious and underlies several common human diseases, including cancer and genetic disorders such as trisomy 21 in Down's syndrome. (journals.plos.org)