Intro and Morals
These days there are many ways to create a baby... the old fashioned way, or in the laboratory. It
should be noted that the term ‘test tube baby’ is wrongfully used in the media... although equally
missing the elegance of the technique, petridishes is where this wonder of nature takes place.
Although much resistance was met when the first in vitro fertilizations (IVF) took place, it has been
proven to be a valuable technique for a myriad of reasons. The main one, in my opinion, being the
ability to screen for genetic disorders of early onset and severe impact, when parents are known to
be carriers of the disease.
Many novel moral issues have come up with the development of sciences, issues which were non-existent
in the past. Is it, for instance, moral to discriminate a healthy baby against a baby with a
disorder? Where do we draw a line?
I see another issue coming into picture, one that many people might not ever have thought of. In the
past five years a revolution has taken place, where marriages of people from the same sexes have been
legalized in numerous countries. With that, comes the legalization of adoptions for same-sex
partners. Can this be taken a step further? Will same sex-partners in the future be able to bond with
the birth of a baby, a union of their genomes?
With the advent of cloning, or a similar technique also based on nuclear transfer, this might very
well be a possibility. But nature might have some tricks for us in store that would pose a
significant barrier.
Fertilization by Nuclear Transfer
Let’s discuss a technique that recently caused controversy in the world of science. Scientist in the US had been working on a fertilization technique in mice, where they were able to conceive mice carrying the genetic information of three parents. The US government banned this work in 1998 and the researchers donated their knowledge to researchers in China. Just last week researchers in China reported that: “Viable human pregnancies.. can be achieved through nuclear transfer”, a ban was issued soon after.
For normal fertilization and embryonic development, the cytoplasm quality of the female egg is crucial. This cytoplasm should contain energy-producing compartments called mitochondria, they are autonomous and carry their own haploid (one copy of each gene) mitochondrial DNA (mtDNA). This mtDNA always comes from the mother, the nuclear DNA (nDNA) on the contrary is contributed both by the sperm and the egg, and is thus diploid (two copies of each gene).
One of the causes of female infertility is a low concentration of mitochondria in the egg, causing the embryo to die around the four cell stage. Scientists recognized, however, that donating cytoplasm from a healthy female enables the embryo to develop full term. Several babies have already been born in this manner, carrying mtDNA from a donor and their mother, and nDNA from both parents.
Nuclear transfer carries this technique a step further, though. The nDNA still comes from both parents, but all the mtDNA now comes from a female donor. The technique in a birds eye view:
the donor oocyte (egg) is fertilized by a donor sperm and a zygote forms (fertilized cell)
the patients oocyte is fertilized by the partner’s sperm and a zygote forms
the pronucleus of the donor’s zygote is removed and is replaced with the pronucleus of the patients zygote
the cell is stimulated by electrofusion and allowed to develop
several cells will be treated in this manner and placed back in the patient’s womb for further development
This is what happened in China, the patient became pregnant with a triplet, the embryos developed to a stage where the heart was beating for all three. At the 33 day stage, fetal reduction was performed, in order to protect the welfare of the mother. Unfortunately, the other two fetuses were miscarried. One was born prematurely by a rupture of the membranes and the other by intrauterine cord prolapse. It is not at all clear if this was due to the technique of nuclear transfer, or was caused by natural complications.
The ban was issued, since too little is known about the effect of carrying DNA from three separate donors. Also due to uncertainty about effects of nuclear transfer manipulations on the embryo, technical information gathered could furthermore be applied to the development of clones.
