Somatic cell nuclear transfer (cloning) : implications for the medical practitioner
Tong, W.F.; Ng, Y.F.; Ng, S.C.
Singapore Medical Journal 43(7): 369-376
2002
ISSN/ISBN: 0037-5675 PMID: 12437047 Document Number: 540590
The current century will bring tremendous changes to the science and the practice of medicine. This century will be acknowledged as the century of Biology as the fusion of molecular genetics and experimental embryology pushes the barriers of science beyond perimeters that we have thought existed, as much as the past century was the century of Physics, with all the exact scientific calculations and predictions, resulting in electricity, nuclear power and quantum physics. The first major breakthrough has been the pioneering work of Wilmut and Campbell, first with the birth of Megan and Moran in 1995, followed by the birth of Dolly the sheep, the first reported mammalian clone from a fully differentiated adult cell, reported in July 1996. However, current cloning techniques are an extension of over 40 years of research using nuclei derived from non-human embryonic and fetal cells. However, following the birth of Dolly, the prospects of cloning technology have extended to ethically hazier areas of human cloning and embryonic stem cell research. Cloning is derived from the Greek word "klon" which means a twig which can replicate itself and grows eventually into a tree. Cloning occurs naturally in many plant species by vegetative means and apoximis. To clone is to reproduce asexually or to make a copy or a set of copies of an organism following the fusion or insertion of a diploid nucleus into an oocyte. A true clone is an individual which has all the components that make up the individual including nuclear genetic material (genome) and other maternally derived factors that is derived from a single unique embryo as a result of sexual reproduction. In the laboratory, cloning in mammals involves replacing the genetic material of an egg with the genetic material of a somatic cell from an embryo or adult which will eventually develop into a full organism or being. This review hopes to bring the reader closer to the science and the ethics of this new technology, and what the implications are for the medical practitioner.