'Bubble Boy' Cured by Gene Therapy in UK

DrKyle writes "Another child with "Bubble Boy" disease aka ADA-SCID (adenosine deaminase deficiency causing severe combined immunodeficiency) has been cured by transforming bone marrow stem cells with the functioning gene. Normally toxic levels of adenosine build up in T-cells killing off those important cells required for a robust immune system. While not the first person cured, another successful case of gene therapy goes a long way in encouraging goverments to continue to fund genetic research."

Comments

Re:Important question

[Kraemahz]

See: Gene Therapy
Specifically this line:
"In theory it is possible to transform either somatic cells (most cells of the body) or cells of the germline (such as stem cells, sperm and eggs). All gene therapy so far in people has been directed at somatic cells, whereas germline engineering in humans remains only a highly controversial prospect. For the introduced gene to be transmitted normally to offspring, it needs not only to inserted into the cell, but also to be incorporated into the chromosomes by genetic recombination."

In order for the altered genes to be passed on the germline would have to be involved in the gene therapy process, which is considered making "designer humans" and thus frowned upon by biological conservatives (read: ethicists).

Other trials were shut down (reformatted!)

[rakarnik]

Three other trials using gene therapy to cure the same disease were shut down by the FDA just last week. Apparently, the "harmless virus" used in a French trial ended up causing cancer in two patients. TFA does not seem to mention these other trials.

Re:Other trials were shut down (reformatted!)

[John Newman]

Nonsense. How can you say that the virus caused the cancer? Nobody knows what caused the death and cancer related to this.

The virus did cause the cancer. In at least one patient, they mapped the site of viral intergration and found that it activated a known oncogene. Unfortunately, this is a currently unavoidable risk* of gene therapy. You have to stick the new genes into the chromosomes for it to work, but if it goes in the wrong place, it could cause a cancer. However, it may well be a reasonable risk given the pre-therapy quality of life of these folks, and the fact that there are effective therapies for leukemias. That one patient whose intergation site was mapped was treated for the cancer, and, AFAIK, is still alive today.

* There are ways to target the site of integration (that's how you create "knock-out" mice), but they only work if you can remove the cells from the body first, culture them for some time, and put them back. We can't do that for blood stem cells quite yet, and it's obviously impossible to do that for things like brains, lungs, and bones.

Re:Important question

[pavon]

To elaborate on what Kraemahz said, the method used in this procedure (and in most cases) does not change the DNA of existing cells while in the body. It just inserts cells with different DNA, that then reproduce. If you inserted bone marrow cells, then the only cells with the different DNA will be more bone marrow cells, and since bone marrow cells take no place in reproduction, the DNA will not be passed on to offspring.

The way it words is that a small number of cells are extracted, and DNA is inserted into those cells using a virus. Viruses are just nature's DNA inserting machines, which usually insert DNA that contains instructions to replicate themselves (which the host cell carries out to it's demise), but in this case just inserts the payload DNA of the the scientists choice. From what I understand, this DNA is not spliced into the existing DNA strand, but rather is just "loose" in the cell. The bio-mechanics of the cell make no differentiation between it and the original strand, so both sets of instructions are carried out simultaneously. This modified cell is the one that is inserted into the patient.

Now if one was to introduce the carrier virus directly into the body, it could inject DNA into all sorts of cells in the body, possibly including the reproductive cells. In addition to being far more controversial, it is also less focused and controllable, and (unless there is a way to make replicating viruses that do not destroy the host cell) would require alot of viri, so in general it is not done.