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Stephanie87-123 t1_j8o02jj wrote

The gene edit is not passed on to the neurons. After a bone marrow transplant, the hematopoietic stem cells can develop in different type of blood cells. Some of these can migrate into the brain, where they can either provide the missing enzyme to the neural cells, or clean up a build up of toxic compounds in the environment of the cells. In the case of MLD, it is probably this removal of toxic compounds that is beneficial.

The bone marrow transplant part is not what is new about this approval. Bone marrow transplants have been used for brain disease like MLD for a while, however a bone marrow transplant from a donor comes with a significant risk of serious complications due to rejection of the tissue. The hope is that gene editing of a patients own bone marrow cells will be much safer. In addition they can sometimes make sure that the edited gene has a higher expression, which may boost the efficacy of the transplantation.

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itsallrighthere t1_j8ozif0 wrote

So if I understand, in the case of genetic metabolic disorders, introducing the missing metabolic function to modified blood cells helps support non modified cells. Do the toxic compounds move from the native cells to the modified cells where they are properly processed?

Do you know where we are in terms of safety for gene therapy?

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Stephanie87-123 t1_j8qwtfn wrote

It really depends on the specific disease and the mechanisms that causes damage to brain cells, but in some cases yes. For most of those disease the toxic compounds will be secreted from the cells, so they are in the extracellular space were the modified cells can take them up and process them.

Gene therapy is not my area of expertise, so someone else might be more up to date on this. The major risk of gene therapy is that the insertion/editing of a gene will lead to unintended disruption of other genes, which worse case scenario might make them more likely to become cancerous. The method used for this treatment, ex vivo gene therapy, were the gene therapy is performed outside of the body is more safe as it allows for extra checks on the cells before they are transplanted back into the patient.

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