The biggest ethical worry about human gene editing is that it will be used to make long-lasting, heritable changes at the embryo stage or on germ (sperm or egg) cells. Posts earlier this year have asked whether we should envision a scenario in which human germline gene editing is accepted in a limited number of cases, with the treatment of sickle cell anemia being proposed as a case in point.
Last weekend, at the annual meeting of the American Society of Hematology, I was reminded that ethical problems often can be avoided by finding a more acceptable alternative approach. In this case, the alternative was somatic stem cell editing of the sickle hemoglobin gene. Briefly, a speaker in one symposium described work in which an infant with the disease would have his or her blood stem cells, which are destined to form blood cells, edited to repair the hemoglobin gene, which is mutated in sickle cell anemia. (A further reminder: there are several techniques for gene editing, all similar in mechanism, not just the CRISPR/Cas9 approach that has drawn the most attention this year.)
Some key points from the presentation, which summarized the current state of work that has been in progress for over a decade:
- The idea would be to harvest the blood stems from the diseased infant, editing them outside the body with a normal DNA sequence, then return them to the patient in a bone marrow transplant procedure similar to current treatment. The advantage is that one would not need to find a marrow donor, who would have to be biologically matched to the patient.
The views, opinions and positions expressed by these authors and blogs are theirs and do not necessarily represent that of the Bioethics Research Library and Kennedy Institute of Ethics or Georgetown University.