They design a test to find defects in embryos before implanting them

Mexican scientists have created a low-cost genetic test to detect unique monogenic defects, that is, hereditary diseases in embryos before implanting them in women seeking the birth of a healthy baby.

The genetic test, developed by experts from the Center for Research and Advanced Studies (Cinvestav) of the National Polytechnic Institute (IPN), is applied during “in vitro” fertilization treatments performed on embryos in early stages before gestation.

In Mexico, around a million and a half couples have a situation of infertility, according to data from the National Institute of Statistics and Geography, so for many of them a viable resource is to resort to assisted reproduction procedures with the intention of achieving a pregnancy. .

“Couples who are aware of suffering from and inheriting this type of disease request to characterize the genetic defect they have in order to later undergo fertilization treatments,” Mexican Cinvestav researcher Esther López-Bayghen Patiño explained to Xinhua.

With this procedure, the embryo with the possibility of being free of the condition is located, “in order to achieve successful pregnancies.”

The detailed treatment consists of carrying out an “in vitro” fertilization cycle, in which the woman is subjected to controlled ovarian-type stimulation, then oocytes are retrieved and fertilized with intracytoplasmic sperm injection.

On the fifth day of embryonic development, it is determined which embryos are of high quality and a biopsy is performed to amplify the complete genome, in order to evaluate the number of sets of chromosomes and verify that it only has two copies of each. genome region.

Once the number of the set of chromosomes is corroborated, the specific genetic defect is sought through the use of molecular biology techniques such as PCR tests and the one without a defective copy of the gene is selected from among several embryos.

“We are pioneers in the world in using whole genome amplification for subsequent diagnosis. We have become experts in using it for other additional genetic diagnoses such as that of these hereditary transmitted diseases”, said Dr. López-Bayghen.

Once the embryos have been selected, they are deposited in the endometrium, where the embryo continues the process of being implanted in the uterus so that the placenta develops, a pregnancy occurs and finally a healthy baby is born.

“What we do is focus directly on finding out if the embryo has the same alterations that come from mom or dad, so the effectiveness of this test is 100 percent. We were not wrong, “said the scientist.

This type of analysis, however, is usually expensive as it includes the evaluation of more than 200 genetic disorders.

“The genetic screening tests offered in the world are three times more expensive than the Mexican one and they are not done here in Mexico. They are all samples that have to be sent abroad and that makes it more expensive for the patient because they have to pay for the transfer,” said the interviewee.

He also advised families that have detected hereditary diseases, to carry out this type of test to avoid the interruption of a pregnancy, in the case of a genetically compromised fetus.

“The message is a message of hope for couples with these genetic problems, because they will be able to be parents,” he said.

“If they approach a serious clinic, their problem can be solved and we can avoid those tragedies that come with the experience of having a first child who is not likely to survive,” said the doctor.

He also assured that with this advance it is now possible to choose an embryo that is healthy, since “we give the option of choosing the embryo without the mutations,” added the specialist.

Experts from the IPN’s center for advanced studies of reference hope that in the future this type of test will detect multigenic and multifactorial diseases.

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