Adapted from Whole-genome risk prediction of common diseases in human preimplantation embryos published in Nature Medicine, March 21, 2022.
Preimplantation Genetic Testing (PGT) of embryos is a common addition to In Vitro Fertilization (IVF) treatment. PGT can screen for roughly 500 diseases caused by a single gene mutation, such as cystic fibrosis. However, most DNA-linked diseases (i.e., heart conditions, autoimmune diseases, cancer, and many other medical conditions) are usually caused by multiple genes.
Since only 2 to 3 cells are removed from the 5-day embryo for PGT, there is not enough genetic material available to examine an embryo's whole genome.
To be able to predict a person's chance of a specific illness from a 5-day embryo, a group of California scientists developed a technique of using a combination of molecular and statistical approaches to "reconstruct" embryos' genomes.
The researchers used PGT data collected during the IVF process and combined them with both parents' more complete genome sequences. In this way, they could predict much of the embryo's DNA.
Once the IVF babies were born, the scientists collected cheek swab samples from the babies and sequenced their whole genome, just as they had done with the parents. When they compared this "true sequence" with the reconstructed genome for the 5-day embryo from which the child originated, there was essentially a match: 98%.
Being able to reconstruct an embryo's genome will provide information for determining an offspring's chances of staying healthy, and it may even one day allow parents to select embryos based on their IQ, height, the color of eyes, and other physical traits in "designer babies".
It remains to be seen whether such embryo selection will be ethically acceptable. What do you think?