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Editor's Comment (by Roger Moorgate)
This exceptional scientific article was written by a close friend of mine who
wishes to retain anonymity. He is a Doctor of Pathology and a compelling
human cloning advocate. Any correspondence regarding this article can be
directed to chaosdriven@hushmail.com,
and submissions of new articles should be directed to rogermoorgate@hotmail.com.
The article is a proficient, clear and persuasive rebuttal of a previous paper
by Rudolph Jaenisch and Ian Wilmut. Dr. Wilmut's paper (called "Don't
Clone Humans") was originally published in Science Magazine, but was
littered with errors, contradictions and a distinct lack of unbiased, open
minded or reasoned argument. In fact, when another colleague of mine Dr.
L. Silver (a Professor of Genetics) tried to publish a rebuttal to the Wilmut
paper, the editorial board of Science Magazine refused to publish. This is
such an absurd concept; a Professor of embryology (Wilmut) writes a
terribly biased and inaccurate paper on genetics and reprogramming, and Science
publishes it. Then a Professor of genetics (Silver) writes a
rebuttal correcting the inaccuracies of Wilmuts genetics paper, and Science
refuses publication. Personally I'd like to believe that politics and
pressure to be politically correct, would not influence a mainstream scientific
journal like Science. Evidence suggests that this ideology could not be
further from the truth. [Editor's Comment by Roger Moorgate, May 14th
2001].
A Rebuttal for Human Cloning
Drs. Jaenisch and Wilmut are neither convincing nor objective in their
treatment of the controversial subject of Human Cloning.
The issue is of significant concern, as the potential use of Somatic
Cell Nuclear Transfer (SCNT) technology as a reproductive option for infertile
couples offers the only means by which a large proportion of these couples
could ever hope to have their own genetically related children, a population
segment constituting as much as 5% of the overall population.
I would like to address specific points made in their paper:
“There are many social and ethical reasons why we
would never be in favor of copying a person”
1. Drs.Jaenisch and Wilmut boldly assert that SCNT will
NEVER
be an acceptable means of reproduction for anyone, under any circumstances,
irrespective of the actual risks involved. They never specify the "many
social and ethical reasons". They are openly biased.
2. Anyone who has given rational thought and study to the matter
understands that a child born as the result of SCNT will be a unique individual,
as unique as any other person, based on studies of identical twins. Dr.Wilmut
himself has commented on the easily distinguishable behaviors seen
in a group of cloned lambs in his lab. Dr.Wilmut is self-contradictory.
3. SCNT is not “copying”! That is obvious to any intelligent
lay person that has given the matter serious consideration. Personally,
I find the use of such derogatory misconceptualizations offensive and,
to use the terminology commonly employed by Dr.Jaenisch “irresponsible”.
“Animal cloning is inefficient and is likely
to remain so for the foreseeable future”
1. A number of studies have already demonstrated far
higher rates of development, as measured in the proportion of live
births to the number of blastocysts transferred, in some cases matching
or exceeding developmental rates seen in human IVF [7,8,9].
2. While the number of cytoplasts utilized is relatively high,
what reason is there to think that this will always remain so? If history
is any indicator, one can reasonably expect that further refinements and
insight to the process will improve efficiency rates even in this relatively
unimportant respect as well. Drs.Jaenisch and Wilmut are not oracles.
“Circumstantial evidence begins to hint at defects
in programming of gene expression in cloned animals.”
"The most likely explanation may be failures in genomic
reprogramming"
“Thus, even minimal disturbance of the embryo's
environment can lead to epigenetic dysregulation of key developmental genes.”
1. These statements illustrate the self-contradictory
nature of their argument.(1,2 vs 3).The entire IETS pre conference symposium
at Maastricht in January 2000 was devoted to the concept that conditions
encountered by the developing embryo go on to affect an individuals lifetime
risk for a number of diseases. Culture conditions during embryo development
have been proven to exert profound effects on the methylation status of
various genes, including some but not all imprinted genes[10].
The IGF2r gene, the aberrant biallelic statement of which in ruminants
which appears to play a prominent role in the development of large offspring
syndrome (LOS), is interestingly enough expressed in a polymorphic pattern
in humans [1,2,3,5].
Of particular interest are some quotes from this reference[4]:
"These results indicate that inactivation of imprinted genes
occurs post fertilization (most likely post implantation) and that genomic
imprinting and gene inactivation are separate processes."
"For these genes, this finding invalidates models of genomic imprinting
that require them to be inactive from the time of fertilization."
2. The argument made is, in their own words “circumstantial”.
The conceptual details which they present of epigenetic programming errors
remain poorly understood. To a large extent we are dealing here with the
old “what came first, the chicken or the egg?” debate, veiled in new clothes.
They clearly point out in their own article that deficiencies of
the culture environment are largely implicated in abnormalities of embryo
development, including being the cause of aberrant DNA methylation patterns,
which then lead to subsequent abnormalities in development.
"There is every reason to think that the human cloning
experiments announced by P.Zavos and S. Antinori will have the same high
failure rates as laboratories have experienced when attempting animal cloning"
1. First, it should be noted that no form of screening
methodology has been systematically employed in any animal cloning experiments
published to date.
2. Several studies have been published demonstrating the birth
of healthy live young and very high success rates[7,8,9].
One of the very references which they site, an experiment involving multiple
cohorts, demonstrated reasonable success rates within the one successful
cohort, leading to the birth of uniformly healthy live offspring [12].
3. Contrary to what Drs.Jaenisch and Wilmut assert, there is
every reason to believe that further refinement of techniques and culture
environments will serve to further minimize developmental deficits seen
in manipulated embryos[14], whether it be in human IVF
or SCNT. Insights gained in minimizing or eliminating deficiencies of the
culture environment will have wide ranging benefits in established forms
of assisted human reproduction such as IVF and ICSI as well.
4. A distinct possibility exists that the overall risk
could be even further reduced. The technique of SCNT completely eliminates
the risk of a number of “normally” seen congenital abnormalities
due to meiotic non disjunction, the most common of which is Down's Syndrome (Trisomy 21), occurring at an incidence of about 1/700[11]
live births in the normal reproductive population.
5. Additional screening methodologies, including but not limited
to; the application of strict morphologic grading criteria, blastomere
biopsy with whole genome chromosomal analysis[15], and
assessment of early embryonic gene expression patterns [16]
can be fully expected to significantly improve success rates as determined
by the final measure of the birth of healthy offspring.
6. Thus, I believe their conclusion to be premature and unwarranted.
Finally, I would like to include this quote from one of Dr.Jaenisch's
own fairly recent publications[6]:
"However, our understanding of molecular details
of the imprinting process, as well as evolutionary considerations, is rather
consistent with imprinting having no intrinsic role in mammalian development."
There is every reason to believe that further elucidation of the molecular
mechanisms involved during the processes of embryogenesis and the
careful tailoring of subsequently developed culture conditions and manipulation
strategies, when combined with appropriate screening methods, will eventually
allow infertile couples to safely have healthy, genetically related children
through Somatic Cell Nuclear Transfer technology.
It is my view that their paper is much more about politics and business,
rather than about science and human welfare. There is little doubt in my
mind, that had such a paper been submitted for publication by graduate
students, it would have been summarily rejected on the basis of being
self-contradictory, grossly misrepresentative of the facts, and openly
biased.
Gentlemen, you are much better at being scientists than politicians.
Return to the fold.
REFERENCES
1: Novartis Found Symp 1998;214:251-9;
discussion 260-3
Making
sense of imprinting the mouse and human IGF2r loci.
Wutz A, Smrzka OW, Barlow DP.
2: Biochem Biophys Res Commun 1998 Apr
7;245(1):272-7
Absence
of an obvious molecular imprinting mechanism in a human fetus with monoallelic
IGF2R statement.
Riesewijk AM, Xu YQ, Schepens MT, Mariman EM, Polychronakos
C, Ropers HH,Kalscheuer VM.
3: Genomics 1996 Jan 15;31(2):158-66
Maternal-specific
methylation of the human IGF2R gene is not accompanied by allele-specific
transcription.
Riesewijk AM, Schepens MT, Welch TR, van den Berg-Loonen
EM, Mariman EM, Ropers HH, Kalscheuer VM.
4: Genes Dev 1994 Feb 1;8(3):290-9
Igf2r
and Igf2 gene statement in androgenetic, gynogenetic, and parthenogenetic
preimplantation mouse embryos: absence of regulation by genomic imprinting.
Latham KE, Doherty AS, Scott CD, Schultz RM.
5: Biochem Biophys Res Commun 1993 Dec
15;197(2):747-54
Functional
polymorphism in the parental imprinting of the human IGF2R gene.
Xu Y, Goodyer CG, Deal C, Polychronakos C.
6: Trends Genet 1997 Aug;13(8):323-9
DNA
methylation and imprinting: why bother?
Jaenisch R.
7: J Reprod Fertil 2000 Nov;120(2):231-7
Cloning
of calves from various somatic cell types of male and female adult, newborn
and fetal cows.
Kato Y, Tani T, Tsunoda Y.
8: Science 1998 Dec 11;282(5396):2095-8
Eight
calves cloned from somatic cells of a single adult.
Kato Y, Tani T, Sotomaru Y, Kurokawa K, Kato J, Doguchi
H, Yasue H, Tsunoda Y.
9: Biol Reprod 1999 Apr;60(4):996-1005
Production
of cloned calves following nuclear transfer with cultured adult mural granulosa
cells.
Wells DN, Misica PM, Tervit HR.
10. Doherty AS, Mann MR, Tremblay KD,
Bartolomei MS, Schultz RM.
Differential
effects of culture on imprinted H19 statement in the preimplantation mouse
embryo.
Biol Reprod. 2000 Jun;62(6):1526-35.
11.Robbins Pathologic Basis of Disease,
4th Edition, p.123-135
12. I.Poleyaeva
et al., Nature 407, 86(2000).
13. Patterson,
D.: The causes of Down's Syndrome. Sci.Am.257:52,1987
14: Toxicol Lett 2001 Mar 31;120(1-3):143-50
Environmental
effects on genomic imprinting in mammals.
Thompson SL, Konfortova G, Gregory RI, Reik W, Dean W,
Feil R.
15: Mol Hum Reprod 2000 Nov;6(11):1055-62
Comprehensive
chromosomal analysis of human preimplantation embryos using whole genome
amplification and single cell comparative genomic hybridization.
Wells D, Delhanty JD.
16: Cell 1998 Oct 30;95(3):379-91 Related
Articles, Books, OMIM, LinkOut
Formation
of pluripotent stem cells in the mammalian embryo depends on the POU transcription
factor Oct4.
Nichols J, Zevnik B, Anastassiadis K, Niwa H, Klewe-Nebenius
D, Chambers I, Scholer H, Smith A.
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