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Meticulous studies must be conducted on preimplantation genetic screening



Original article: http://the-japan-news.com/news/article/0001935588

(The Japan News)

Clinical studies on so-called preimplantation genetic screening (PGS) are likely to be launched within the year.

PGS is a method in which all the chromosomes of embryos created through in vitro fertilization are examined so that only embryos determined to have no chromosomal abnormalities can be implanted into the uterus.

The ethics committee of the Japan Society of Obstetrics and Gynecology has given its go-ahead to a PGS clinical research program. Can the preimplantation genetic profiling program prove to be of help to women afflicted with infertility? The medical effectiveness of the genetic screening technology should be examined and evaluated with sufficient circumspection.

One factor behind such problems as infertility and miscarriage is chromosomal abnormalities in embryos due mainly to advanced maternal age. As there is an increasing number of births among women of advanced age in Japan, cases of in vitro fertilization as a form of fertility treatment have been on the rise. However, there are many cases of repeated in vitro fertilization failures, resulting in mental and physical strain for the patients.

In the planned clinical research, preimplantation screening will be conducted on 300 women who have either experienced at least two miscarriages for unknown reasons or who have failed to get pregnant at least three times through in vitro fertilization. Whether the fertility rate and other favorable effects can be enhanced in comparison to cases in which PGS is not practiced will be scrutinized in the preimplantion genetic profiling.

The obstetrics and gynecology society’s intention to verify scientifically the effectiveness of the preimplantation screening is understandable.

However, there is criticism that such screening could lead to the arbitrary “selection of who should live.” This is because PGS will eliminate embryos that could result in the birth of a baby with chromosomal abnormalities such as Down syndrome.


Prevent abusive practices

The academic society has so far approved only preimplantation genetic diagnosis (PGD), which is limited to serious hereditary diseases and chronic miscarriages. PGD examines specific chromosomes, but all chromosomes are examined in PGS.

The fact that the society has given specific approval for this clinical PGS program, while continuing to ban the general practice of genetic profiling under its official guidelines, should be considered a last-resort measure taken inescapably under the pressure of necessity.

Behind its decision is the fact that the technical level of PGS has been improved remarkably, and that an increasing number of people have been calling for application of the latest genetic profiling.

In 2013, a new type of prenatal diagnosis was started, to examine the blood of an expectant mother to check for conditions such as Down syndrome in the baby. Some involved in obstetric treatment have said the society’s current ban on identifying such abnormal chromosomes through PGS should be criticized as representing a double standard on the part of the society.

Some medical institutions have already put PGS into practice, contrary to the society’s guidelines. This vividly demonstrates the present state of affairs in which discussions on the ethical aspects of the matter cannot keep up with rapid advances in reproductive medicine.

The society plans to embark on final studies of the pros and cons of introducing PGS if and when its effectiveness is ascertained through the three-year clinical research program.

If the introduction of PGS for general practice is approved, it will become an important task to work out measures to prevent the abuse of preimplantation screening technology. By examining chromosomes, it will become possible to preselect the sex of a baby. PGS should not be allowed to be used for purposes deviating from the original aim.

Discussions must be deepened among a wide range of experts, not just medical doctors, about the implications PGS might have for society.


Stork Fertility Center:
1. Although PGS is not allowable in Japan so far, it does help the patients to increase the success rate. 
2. Do I need to do PGS?
The patients are recommended to take PGS test,
a. Advanced age
b. Recurrent miscarriage (more than two)
c. Male infertile factors
d. Repeated failures in the IVF programs
e. Reported chromosome abnormalities
3. New platform to PGS test:
Nest generation sequencing (NGS( is now applied in the PGS realm and could provide better accuracy. 
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