Flaws in mitochondrial genes have been found to lead to certain types of blindness and epilepsy and may also contribute to some degenerative disorders, such as dementia, which are associated with aging. In even more fundamental ways, discoveries in genetics have led to novel strategies for treating disease. Decades ago, scientists learned that DNA is mainly the archive of genetic information. The bottom line in any kind of biomedical research lies in the realm of treatment and prevention. The ultimate step in that direction is gene therapy - the deliberate transplantation of genes to treat or even prevent human disease.
Many geneticists dismiss gene therapy as a distant prospect, but others disagree.
We are probably going to have it soon. Gene therapy was actually tried in 1970 and again in 1980 without success, but the knowledge and techniques were primitive by today's standards. The child suffered from a grave immune deficiency because she lacked the enzyme adenosine deaminase. The doctors took her own white blood cells, altered them by adding the gene for the missing enzyme and transplanted the altered cells back into her. Ultimately the same approach may be applied to other types of cancer.