This article appears in the November 2000 edition of the Catholic Medical Quarterly

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Has Molecular Eugenics Arrived?


A couple in Colorado has used in vitro fertilisation and pre-implantation genetics to produce embryos and have them screened for a child who could be a stem cell and bone marrow donor for their daughter. Adam Nash, who now becomes a 'world s first , was conceived after tests to ensure that his cells were suitable for a life saving transplant for his six year old sister Molly, who suffers from Fanconi's anaemia. Molly is now recovering from the cell transplant from five week old Adam s umbilical cord in a sealed room in the University Hospital, Minneapolis. Adam sleeps in a carry cot on a bedside table beside her.

The couple went through IVF and genetic evaluation four times without success. Molly's blood counts were getting worse and the family's finances were disappearing. On their fifth attempt, one of 15 embryos was both healthy and a bone marrow match. The others presumably were discarded. Mrs. Nash heard she was pregnant on Christmas Eve; Adam was born on August 29; the transplant took place at the end of September.

Dr. Wagner, the scientific director of the Stem Cell Institute at the University of Minneapolis, told The Times "We could have considered using an unrelated donor transplant, but the chances of a cure were only about 40%. Using a sibling for a match, you can more than double those chances." He admitted that they had opened a Pandora's box of medical issues and were sitting on a slippery slope. "This technology" he adds "need not be unique to Molly's disease, Fanconi's anaemia, which causes defective bone marrow. It could be used for any disease where there is a gene that is clearly abnormal, such as sickle-cell disease. We have about ten families in the queue waiting to go through the same process with various diseases."

Presented in that way it appears to be a humane use of advances in genetic medicine, the parents have a second healthy child with a strong possibility that Molly will be cured of a condition which would otherwise most certainly end her life prematurely. Again, many commentators point out that it may soon be possible not only to identify defective genes but to replace them with 'healthy ones, with allegedly great benefits in the control of cancer and other chronic conditions. It could also of course be used to create 'designer babies'.

But when it is remembered that during the five attempts at obtaining a suitable embryo probably over 100 embryos were sacrificed, a manifest injustice was conducted: 100 human beings with potential sacrificed to obtain the desired one. Its objective, to double the chances of success from forty to eighty per cent, supports the view of a modern technology devoid of any system of values. There are alternative ways of obtaining stem cells: the most promising and least likely to attract the 'slippery slope' argument is that using adult stem cells. Evidence, from the Karolinska Institute in Sweden and the Institute for Stem Cell Research in Milan, has confirmed that nerve stem cells from adults are more flexible than previously thought. The scientists succeeded in 're-programming' neural stem cells (taken from an adult volunteer) to behave like muscle cells. The Imperial Cancer Research Fund has announced that British scientists had taken the first step towards methods of growing liver tissue for patients from their own bone marrow. Another alternative has been announced by the Leukaemia Research Fund. It is assembling a national bank of stem cells taken from umbilical cords which should be able to provide an appropriate match for almost every transplant patient.

Allowing for the possibility of huge potential benefits from research on stem cells derived from whatever source, what is the evidence that the replacement of defective cells is going to be effective in curing these conditions? Richard Nicholson in The Tablet (September 30th) points out that the balance sheet for gene therapy world-wide is cures: nil; deaths: 5 (at least); cases of serious adverse effects: more than 1,000.

Dr. Neil Holtzman, at John Hopkin's Medical Institute, and Dr. Theresa Marteau, of Guy s, King's and St. Thomas' Medical School, underline this pessimistic outlook in the New England Medical Journal by commenting that having a gene conferring the risk of a certain disease does not make it inevitable that it will develop.. Most of such genes are regarded as of low penetrance, as otherwise during evolution they would have been selected out. Their carriers would be less likely to have children. However, diseases manifesting themselves after the reproductive years, such as Alzheimer's, may result from the carrier. But even if those cases where it is known there is a high risk of the disease developing, its awareness does not necessarily make an effective treatment certain, as in sickle-cell anaemia. The authors point out that the molecular basis of sickle-cell anaemia has been known for forty years, but no effective treatment has yet been found. Perhaps Dr. Wagner is going to prove them wrong.

Genetic testing is now actively promoted. It is regarded as a fine method of prediction: an advance warning of the diseases that are in prospect for us in later life. But, unless the gene is rare and its effects powerful, the predictive power of the tests is low, and such instances are likely to represent a small proportion of the total. Two or more defective genes must be present and be present simultaneously for a prediction to be valid. So far there are few treatments available to those carrying a predisposition to any disease. The authors tend to agree with Richard Nicholson when they state "No interventions based on the identification of disease-related genes have yet proved safe and effective".

Possible exceptions are breast and colonic cancer where prophylactic surgery or careful monitoring might prolong life in those unfortunate enough to carry the defective agents.

Many, faced with the low predictive value of the tests and the lack of adequate treatments, will simply choose not to be tested at all, say the authors. In conclusion, they assert "Testing in families with a history of the disease would be a more efficient approach, but does not a revolution make. Differences in social structure, lifestyle and environment account for much larger proportions of disease than genetic differences".

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