Gene therapy has been shown to have great potential, but has been difficult to administer effectively and for some, has had tragic side effects. In one of the most well-known incidents, a few children cured of a rare disease through gene therapy developed leukemia, from which one died. Despite this terrible setback, researchers now believe they have developed new gene insertion methods that do not lead to cancer. From the NYT:
The latest encouraging news arises from a paper published Friday in the journal Science. An international team of researchers are reporting the successful treatment of two children with adrenoleukodystrophy, or ALD, in which the fatty insulation of nerve cells degenerates. A result is progressive brain damage and death two to five years after diagnosis. The disease was the focus of the movie “Lorenzo’s Oil.”
Scientists say they believe they avoided the cancer problem by using a different method to get genes into the children’s DNA. Two years have gone by, and the children are doing well.
The children were not cured, but their disease was arrested. And gene therapy was as good as the standard treatment for the disease, a bone marrow transplant. In this case, the children could not have a transplant because they did not have marrow donors that matched them genetically.
In addition, a paper last month in the journal Lancet reported that a different method of gene therapy, which did not involve inserting a new gene into DNA, partly restored the sight of five children and seven adults with a rare congenital eye disease, Leber’s congenital amaurosis. People with the disease have a mutated gene that prevents them from making a retina protein.
While not in the DNA, the added gene remains in the body of the cells, directing the production of the missing protein and helping correct the disorder. The patients had no standard treatment, and gene therapy offered them a chance to see again, although their sight was far from perfect. But the gene is not copied when cells divide, as it would be if it were part of the cells’ DNA, so the method is applies only to cells, like those of the retina, that divide rarely.
The possibilities for gene therapy are nearly limitless – not only might it be used to treat chronic diseases where existing treatments are lacking, but could also be used, as Ramez Naam writes in his book More Than Human, to increase muscle mass, correct obesity, change skin tone, cure baldness, change eye or hair color, and more.