Pre-implantation Genetic Diagnosis is performed before the implantation in order to establish if there is a risk of transmitting a genetic disease to the child. If that is the case the entire process could be terminated to avoid the abortion. However not all genetic diseases can be diagnosed using this technique. The causes of a genetic disorder could be linked to chromosomal abnormalities depending on the sex or could be an abnormality caused by a single gene.
Here are the steps of the PGD process:
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The biopsy is carried out with the help of a microscope without interfering with the normal development of the embryo. A needle is inserted in the shell of the embryo and a single cell called blastomere is gently extracted and becomes the subject for analysis. There are 3 techniques of performing this analysis:
1) The first one is called Fluorescence in situ hybridization analysis (FISH) and uses fluorescent probes which are specific for each chromosome. The probes can be visible with a fluorescent microscope. At this point 5 chromosomes can be detected in a single cell using the FISH technique: X, Y, 13, 18 and 21. This technique is also used for determining the sex in diseases linked with sex and for numerical abnormalities on the chromosomes.
2)The second is called Polymerase chain reaction (PCR) and is used for detecting a single gene mutation. PCR technique allows the amplification of a fragment of genetic material which was extracted from the nucleus.
3)Haplotyping is the newest technique and uses genetic material fingerprinting in order to identify the chromosomes which might carry abnormal genes.
Once they were analyzed the embryos are stored in culture where they can divide. Afterwards the healthy embryos are transferred into the uterus and in vitro fertilization procedure can continue.
The PGD should be taken into consideration by couples who had a baby that carries a genetic disease if they plan to have another or by couples that had repeated attempts of getting pregnant and couldn’t succeed because of genetic disorders.
Despite its benefits the PGD has its controversies. People are worried that PGD will be used for sex-selection and this way we will confront to an unbalanced sex ratio.They tent to confuse it with genetic engineering.
On the other hand there are voices that say that if the medicine has evolved on such a manner why shouldn’t we take advantage of it? If a patient wants to choose the sex for his baby why shouldn’t that be possible?
In the end people have the right to choose what kind of medical technology they want to use and if they want to use it.