The research related to in vitro fertilization and preimplantation genetic testing (PGT) has been ever-evolving. The new technique, designed by a silicon valley company, deciphers the genetic code of the embryo to calculate its future risk of having cancer, diabetes, and ten other common diseases.
The article “Whole-genome risk prediction of common diseases in human preimplantation embryos”- published in Nature talks about the novel technique of testing embryos and presaging a day when parents could select children with a greater chance of living a healthier life.
Developed by Dr. Akash Kumar et al., a pediatric medical geneticist and co-founder of MyOme- a Menlo Park-based genome sequencing company, hopes to provide genetic information of the embryos relevant to the diseases and help intended parents make empowered choices.
In this Article
The new PGT technique: Assessment of embryos for multiple common yet complex diseases
The research team, consisting of a collaboration of physicians, bioinformatics experts, computer engineers, and others with MyOme, the San Carlos DNA testing company Natera, and the Bay Area-wide fertility clinic Spring Fertility enrolled 20 couples using IVF.
With the help of powerful computational tools for parental and embryonic DNA, the team reconstructed the entire genome of 110 five-day-old embryos from 10 couples who had undergone IVF. The genome showed 98% accuracy with that of the baby’s genome. When matched against the genome of the resulting baby, it was 98% accurate, showing more effectiveness than the current approach of sequencing only the embryonic DNA.
Then they scrutinized the genome to predict the embryo’s risk for common diseases like breast cancer, colorectal cancer, pancreatic cancer, prostate cancer, atrial fibrillation, coronary artery disease, Crohn’s disease, ulcerative colitis, lupus, vitiligo, and Type 1 and Type 2 diabetes that may develop in the later years.
Employing the vast genetic information of adults with these diseases, they could calculate the probability of the embryo developing a disease and assign ‘risk scores’ to each embryo tested. For instance, some embryos in the study had double the risk of atrial fibrillation than others.
And in one instance, 13 of 20 embryos from a couple with a family history of breast cancer showed an increased chance of breast cancer and ovarian cancer as the embryos were found to carry the pathogenic BRCA1 mutation.
Unlike the previous PGT modules that are used to predict rare Mendelian disorders, this life-tinkering advanced testing technique is still in its research phase. The commercial availability of this module applying to the IVF or ICSI embryos could relieve the worry and burden of many families having specific diseases run through their families and generations.
When we look into the benefits to the health systems, this technique can help the selection of healthy embryos and reduce the number of people born at risk of these illnesses.
The stumbling stones to wide availability
The new but controversial aspect of this testing is the technique’s ability to assess an embryo’s risk for much more common yet complex and treatable inherited diseases, such as breast and prostate cancer. And risk prediction for these diseases until now has been done only in adults and not embryos.
However, the clinical utility of the new testing remains to be proven, While the testing technique raises ethical and legal questions- “When is it right for prospective parents to do quality control?”
Bioethicists demand a broader societal discussion before the testing moves beyond the research setting. They believe that the most common disorders are influenced not only by genetics alone but also by environment and habits.
If these tests are proven to be accurate or made available to the public, standards of reliability and accountability need to be defined. And parents will need to be well counseled before they make their decision about taking the test.
Talking of the futuristic perspective, researchers believe that these testing techniques may help develop new and effective treatments for these diseases by the time today’s embryos become adults.
Akash Kumar et al, “Whole-genome risk prediction of common diseases in human preimplantation embryos”, Nature Medicine (2022). DOI: 10.1038/s41591-022-01735-0