TOKYO -- The Japan Society of Obstetrics and Gynecology (JSOG) is considering beefing up clinical research on preimplantation genetic testing (PGT) of embryos produced via in vitro fertilization (IVF) starting next year, it announced at a Dec. 16 symposium.
PGT involves screening all chromosomes of embryos produced through IVF for abnormalities. JSOG began a clinical study in February 2017 in which it conducted PGT, and only implanted embryos found not to have any abnormalities. But the research results announced Dec. 16 failed to show sufficient grounds for the test's effectiveness.
The society revealed that it would consider shifting its clinical study into full gear next year by increasing the number of participants and facilities.
PGT has been criticized as a tool for the "screening and selection of life," out of concerns that it would lead to the elimination of embryos with chromosomal abnormalities such as Downs Syndrome. Because of such apprehensions, JSOG had heretofore banned such testing in its official guidelines, and reprimanded some private clinics in Japan that carry out the tests.
The tests are used in other countries to prevent miscarriages, however, and JSOG decided to launch a clinical study on the effects of PGT on the Japanese population.
The subjects were 85 women between the ages of 35 and 42, including those who did not get pregnant after three or more attempts of IVF, and those who experienced two or more miscarriages.
Of the 77 women on which JSOG has data, 38 were able to have embryos implanted in their uterus, 27 became pregnant, and three miscarried. The miscarriage rate was 11 percent, and JSOG indicated that compared to the 29-percent miscarriage rate among women who underwent fertility treatments, according to JSOG statistics, this was an "improvement."
However, JSOG also said that its clinical research ran behind schedule. It will therefore be releasing data on women who did not undergo PGT serving as "controls," and data on the main purpose of the study -- birthrate -- at a later date.
The research that has been conducted thus far is considered a preliminary phase of the study. "We're still a long way away from being able to use this in general medical practice, but we hope to deliberate how to introduce (PGT) to Japan in the form of clinical research," said JSOG Ethics Committee chairperson and Tokushima University professor Minoru Irahara. "Hopefully we'll enter the next stage of research around March of next year."
PGT that is currently being studied looks for excesses or deficiencies in the usual 23 pairs of chromosomes that comprises a total of 46 chromosomes. Embryos with too many or too few chromosomes are discarded. This means that embryos with one too many of the 21st chromosome, which causes Down syndrome, or embryos with only one sex chromosome, which causes Turner syndrome, are disposed of.
In the past, JSOG had banned the elimination of embryos that were otherwise likely to eventually be birthed. However, embryos with chromosomal abnormalities have trouble being implanted and are more likely to be miscarried than embryos with no chromosomal abnormalities -- raising hopes for the application of PGT as a treatment for infertility.
The screening method had heretofore been called by JSOG as PGS, or preimplantation genetic screening. But the organization has changed its name for the procedure to adhere with what it is commonly called around the world: PGT-A, or preimplantation genetic testing for aneuploidies. Aneuploidy refers to the presence of an abnormal number of chromosomes.
The name may be different, but the testing method remains the same. The ethics of such testing was debated at the Dec. 16 symposium. "Even if the test is carried out for the purpose of preventing miscarriages, we cannot say that the procedure is not the screening and selection of life," pointed out Meiji Gakuin University professor Azumi Tsuge, who is well versed in assisted reproductive technology.
Nobuko Mikata, the head of an organization for people with intractable diseases, said, "We are the people who get killed. Please make our society one that is accepting of all people."
Meanwhile, those who experience recurrent miscarriages or infertility could be heard voicing comments such as, "We want a society in which these tests are offered as a choice," and "We want these tests to be made available right away."