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BMA position on human 'cloning'

Debate on human cloning has been seriously hampered by the use of the word 'cloning' to refer to a wide and very diverse range of activities. It is essential that those discussing the subject are aware of the fundamental differences between the various activities included within this broad heading.

The principal distinction to make is between:

• Those techniques which involve the deliberate creation of genetically identical individuals (often called 'reproductive cloning'); and
• Those activities that use similar techniques but where the aims, objectives and outcomes are fundamentally different. With activities that fall into this group (sometimes referred to as 'therapeutic cloning') there is no intention to create genetically identical individuals.

A brief account of the various activities included within these two categories, and the BMA's views on each, are summarised below. A more detailed analysis of the issues, however, can be found in a BMA discussion paper, prepared for the World Medical Association.

'Reproductive cloning'
'Reproductive cloning' involves the creation of genetically identical beings. There are essentially two different methods for achieving this aim.

Cell nuclear replacement
Cell nuclear replacement was the technique used to bring about the birth of Dolly the sheep in 1997. This involves inserting the nucleus (containing DNA) from a cell from the person or animal to be cloned into the cytoplasm of an unfertilised egg which has had its own nucleus removed. The egg is then stimulated to begin cell-division and the resulting embryo, at an appropriate stage, is placed in a uterus for growth and development in the usual way. The embryo will have nuclear DNA (which contains the vast majority of the genetic material) identical to the nucleus donor, but the mitochondrial DNA (containing a small amount of genetic material), which is found in the cytoplasm of the egg, will be from the egg donor.

In theory, this technique could be applied to bring about the birth of humans with the same genetic make up as an existing or previously existing person (although there are doubts about whether this procedure would ever be safe and efficacious in humans). The idea that individuals created in this way would be an exact "copy" or "replica" of the original person, however, is based on extreme genetic determinism. The individual will be born at a different time, into a different social, political and economic environment with different choices and life-chances. Personality traits and abilities are only partially genetically determined and our behaviour and opinions are affected, to a very large extent, by our physical and social environment.

Embryo splitting
Another type of reproductive cloning, which has been proposed, is the splitting of an in vitro embryo, at an early stage of development, to deliberately produce identical twins. It has been suggested that this technique could have benefits for those undergoing fertility treatment where only one embryo is available for transfer, by splitting the embryo into two thereby, theoretically, increasing the chance of a successful pregnancy. There are, however, very serious doubts, based on experience from animals, about whether this technique is ever likely to be a realistic option for humans. Although the success rates for in vitro fertilisation (IVF) are consistently higher when two embryos are replaced rather than one, this may be linked to the quality of the embryos rather than the number replaced. Arguably, splitting, even a good quality, embryo into two will not increase the chance of pregnancy because it will result in two poor quality embryos which are unlikely to implant.

If the embryos created in this way were replaced in a single treatment cycle of IVF, the procedure would simply mimic nature which sometimes results in an embryo splitting to produce monozygotic twins. It has been suggested, however, that one or more of the embryos produced in this way could be stored and implanted at a later date - resulting in identical twins being born years apart - or an embryo could be kept in storage to provide a "perfect replacement" in the event of the child's death. It is possible that regulations could be put in place to prevent such occurrences, such as insisting that all cloned embryos are replaced in one treatment cycle. But, the potential benefits would apply to a very small number of people and it is questionable whether the potential benefits would be sufficient to outweigh the possible damage to public confidence, of crossing the currently accepted moral boundary, by permitting any form of reproductive cloning.

The BMA's view on 'reproductive cloning'
The BMA considers unacceptable the notion of cloning whole humans and would not wish to see public policy develop in this way. Many people instinctively reject the notion of deliberately creating genetically identical individuals. Whilst the BMA sympathises with such reactions, acknowledging the need to take on board the public's "gut response", it also recognises the importance of clearly articulating the reasons for this opposition. Terms such as "human dignity" and "the intrinsic value of the individual" are frequently used in this debate to justify opposition to reproductive cloning; the BMA would like to see further debate about the meaning of these phrases and how they relate to reproductive cloning. Thus, while the BMA does not support reproductive cloning, it would like to see further, rational debate about the subject in order to ensure that public policies in this sphere can be supported by the strength of argument, and not solely by the strength of opinion.

'Therapeutic cloning'
'Therapeutic cloning' does not involve the creation of genetically identical individuals but uses some of the same techniques and has thus been included within the broad heading of 'cloning'.

The production of compatible tissues for transplantation
Of the activities that fall into this second group, the one that has received the most attention is the possibility of generating compatible tissue for transplantation.

This would involve transferring the nucleus - containing the genetic material - from one of the patient's own somatic cells - into a donor egg that has had its own nucleus removed. The egg would then be stimulated so that it begins to divide but it would only be allowed to develop to the stage needed to separate and culture embryonic stem cells.
It is believed that these embryonic stem cells could then be stimulated to develop into whatever tissue was needed by the patient:

• neural tissue for the treatment of degenerative diseases such as Parkinson's disease;
• bone marrow for leukaemia sufferers;
• muscle tissue for the repair of a damaged heart; or
• skin for treating burns victims.

This work has the potential to benefit vast numbers of people. Not only could it potentially offer a means of overcoming the severe shortage of tissue available for transplantation but also, because the tissue would be generated using the patient's own genetic material, there would be no need to take the strong immuno-suppressive drugs which can be harmful when taken over a long period of time. While the suggestion that whole organs could be developed using this technology may be overly optimistic, it is feasible that a damaged organ could be repaired using compatible tissue where currently a replacement organ would be required.

This work is inevitably controversial because it involves the use of human embryos for research and some people have a moral objection to this. Nevertheless, in 1990 Parliament debated the issue of embryo research and agreed that it should be permitted up to 14 days after fertilisation with a licence from the Human Fertilisation and Embryology Authority. The BMA supports carefully controlled research involving human embryos. The criteria for which embryo research is permitted in the UK are strictly limited and in 2001 new regulations were made to permit the HFEA to license this type of research.

The avoidance of mitochondrial diseases
The term "therapeutic cloning" has also been used to refer to the use of cell nuclear replacement techniques for the avoidance of severe life-threatening diseases caused by defects in the mitochondria, found in each cell. If the woman has the disease herself, all of her egg cells will carry some of the defective mitochondria and thus, all of her children may be affected. This risk could be avoided by transferring the nucleus from her own egg to a donor egg which has had its nucleus removed, before fertilisation. The resulting embryo would not be identical to any other embryo or person and therefore is not a clone but this has been included within the broad heading of "cloning" because of the technique used.

Basic research
Some areas of basic research - such as research into ageing and the development of tumours - have also been included within the broad heading of "cloning" because of the techniques used.

The BMA's view on 'therapeutic cloning'
The BMA supports the use of carefully controlled research, including research using human embryos where necessary for :

• the development of tissue for transplantation; and
• the development of methods of therapy for mitochondrial diseases.

The BMA would also wish to see the continuation of important basic research provided this is strictly controlled and regularly monitored.