Diamond–Blackfan anemia (DBA) is a rare, dominant genetic disorder characterized by bone marrow malfunction, birth defects, and a predisposition to certain cancers. Infants with DBA usually develop anemia in the first year of life, have lower than normal production of red blood cells in their bone marrow, and have a high risk of developing leukemia and bone cancer. At the molecular level, DBA is caused by mutations in any one of 10 genes that encode ribosomal proteins. The first-line therapy for DBA is steroid treatment, but more than half of affected children develop resistance to the drugs and in these cases, treatment is halted. DBA can be treated successfully with bone marrow or stem cell transplants from donors with closely matching immune system markers. Trans- plants from unrelated donors have significant levels of complications and mortality. QUESTIONS: 1. Given that a faulty ribosomal protein is the culprit and causes DBA, discuss the possible role of normal ribosomal proteins. Why might bone marrow cells be more susceptible to such a mutation than other cells? 2. A couple with a child affected with DBA undergoes in vitro fertilization (IVF) and genetic testing of the resulting embryos to ensure that the embryos will not have DBA. However, they also want the embryos screened to ensure that the one implanted can serve as a suitable donor for their existing child. Their plan is to have stem cells from the umbilical cord of the new baby transplanted to their existing child with DBA, thereby curing the condition. What are the ethical pros and cons of this situation? 3. While a stem cell transplant from an unaffected donor is currently the only cure for DBA, genome-editing technologies may one day enable the correction of a mutation in a patient’s own bone marrow stem cells. However, what specific information would be needed, beyond a symptom-based diagnosis of DBA, in order to accomplish this?
Diamond–Blackfan anemia (DBA) is a rare, dominant genetic disorder characterized by bone marrow malfunction, birth defects, and a predisposition to certain cancers. Infants with DBA usually develop anemia in the first year of life, have lower than normal production of red blood cells in their bone marrow, and have a high risk of developing leukemia and bone cancer. At the molecular level, DBA is caused by mutations in any one of 10 genes that encode ribosomal proteins. The first-line therapy for DBA is steroid treatment, but more than half of affected children develop resistance to the drugs and in these cases, treatment is halted. DBA can be treated successfully with bone marrow or stem cell transplants from donors with closely matching immune system markers. Trans- plants from unrelated donors have significant levels of complications and mortality.
QUESTIONS:
1. Given that a faulty ribosomal protein is the culprit and causes DBA, discuss the possible role of normal ribosomal proteins. Why might bone marrow cells be more susceptible to such a mutation than other cells?
2. A couple with a child affected with DBA undergoes in vitro fertilization (IVF) and genetic testing of the resulting embryos to ensure that the embryos will not have DBA. However, they also want the embryos screened to ensure that the one implanted can serve as a suitable donor for their existing child. Their plan is to have stem cells from the umbilical cord of the new baby transplanted to their existing child with DBA, thereby curing the condition. What are the ethical pros and cons of this situation?
3. While a stem cell transplant from an unaffected donor is currently the only cure for DBA, genome-editing technologies may one day enable the correction of a mutation in a patient’s own bone marrow stem cells. However, what specific information would be needed, beyond a symptom-based diagnosis of DBA, in order to accomplish this?
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