Sunday, 25 March 2012

PREIMPLANTATION GENETIC DIAGNOSIS: TODAY AND TOMORROW                                                                         By Meg Cloake                                                               

                                                                                                    Figure 1.         All 23 Chromosomes of the Human Genome

Preimplantation Genetic Diagnosis (PGD) is a complicated process whereby genetic material is manipulated in order to ‘play God’ and create the next generation of future human beings. PGD is an advance in gene-screening technology that has enabled the establishment of embryos with chromosomal abnormalities to take place (Yeh, 2002).  So Basically, PGD is a form of pre-natal screening that analyses the genes of an IVF embryo to see if any genetic diseases are coded for, within the individual's genome. 

During PGD, one or two of the cells extracted from the blastomere (an embryo consisting of 8 cells) is used for analysis (Pennings and de Wert, 2011). This analysis is completed through either Polymerase Chain Reaction (PCR) or Fluorescence In-Situ Hybridastion (FISH) technology, whereby chromosomes are screened for these gene abnormalities which can lead to genetic disease (Yeh, 2002).  If mutations are detected then it becomes the parents’ and their doctor’s decision whether or not the embryo is to be implanted for pregnancy.  PCR and FISH are two types of technology that are used to either copy (PCR) or probe (with fluorescent probes (FISH)) DNA coding and therefore detect any abnormalities, in relation to the intergrity, number of  (possible aneuploidy) or absence/presence of sequences, within the DNA base sequence (ibid). 

PGD has been used to screen for diseases like; Tay-Sachs, Cystic Fibrosis, Spinal Muscular Atrophy and Down Syndrome (just to name a few)(Kopp, 1996). PGD has even been used as a form of sex-selection.  At first, sex-selection was used to eliminate genetic diseases within children. Severe forms of mental retardation as well as Duchenne Muscular Dystrophy and hemophilia only affect males. With this being so, couples who were carriers of these diseases opted to only implant female embryos (ibid).  However, as the years passed, couples began requesting sex selection for no other reason than to create their own ‘perfect’ family consisting of their most favoured male:female ratio. This use (or ‘abuse’) of PGD began to raise some serious questions concerning morals and ethics within the field of genetic technology.  The question was posed, “Should parents be allowed to choose characteristics for their children that are not related to disorders, such as their baby’s eye colour, personality, or even the sex of their baby?” (Wekesser, 1996, p.403).  What do we all think? If they're our children is it up to us to decide what they look, act or think like?

                                          Figure 2.      The separation of A Double Helix DNA Strand During PCR. 

So, we all know that the exciting field of genetics had a major explosion in its technology in 2003 when the sequencing of the human genome was completed. This enabled a complete mapping of humans’ 23 chromosomes (Reece et al., 2011).  It worries most scientists and ethicists though, as humans discover more about the human genome, that it may soon be common knowledge where the chromosomes for hair and eye colour, body composition, academic potential and sporting potential lay (Kopp, 1996).  These locations of course have not yet been uncovered yet most scientists agree that its only a matter of time.

Due you think the use of GPD will reach a point where  the physical characteristics of a zygote are dictated by the parents?  
If so, which traits do you think will become most popular?
Will this result in the rejection of 'non-designer children' within society?
Will this lead to the groups of people who possess these so-deemed 'unworthy' traits fighting back? Arguing that their traits aren't 'unworthy?'
Could this lead to great social upsets and possibly violence or uproar?
Will genetic difference become rare because of PGD treatment and 'designer babies'?
Could this hence lead to some people trying to breed out certain hair colours or body compositions?

Encyclopedia of Applied Ethics: PGD

Kopp's review of PGD

PGD Fact Sheet:

                                                                       REFERENCE LIST 

Kopp, R, 1996, Preimplantation Genetic Diagnosis, viewed 16 March 2012,

Pennings G, de Wert G, 2011, ‘Preimplantation Genetic Diagnosis’, Encyclopedia of Applied Ethics, 2nd edn, pp. 576-583. 

Reece, J, Meyers, N, Urry, L, Cain, M et al. 2011, Campbell Biology: Ninth Edition, Pearson Australia Group Pty Ltd., China. 

Wekesser, C, 1996, Reproductive Technologies, Greenhaven Press, Inc, San Diego. 

Yeh, M, (University of Queensland) July 2002, Preimplantation Genetic Diagnosis, viewed 16 March 2012, <>.

                                                                    IMAGE BIBLIOGRAPHY

Figure 1:
Morris, R 2012, PGD Preimplantation genetic screening, IVF1, viewed 18 March 2012, .

Figure 2:
Morris, R 2012, PCR in PGD, IVF1, viewed 18 March 2012,

1 comment:

  1. Preimplantation genetic diagnosis, or PGD for short, is a procedure that may accompany certain assisted reproductive technologies (ART) that work to create embryos through the combination of sperm and eggs. The purpose of PGD is to identify chromosome abnormalities and genetic defects in embryos to determine if the particular embryo should be transferred to the uterus. The procedure also allows for sex selection, which carries ethical questions for some.

    PGD Preimplantation Genetic Diagnosis