Preimplantation genetic testing (PGT) refers to the screening of embryonic chromosomes before embryo implantation to exclude embryos carrying genetic diseases and chromosomal abnormalities to effectively reduce birth defects and is one of the most valuable tools in assisted reproductive technologies to improve pregnancy success rates. However, due to the limited genetic material in embryos and the imprecision associated with allelic deletions, a comprehensive analysis of the embryo genome is costly and time-consuming.

In a study entitled "Whole-genome risk prediction of common diseases in human preimplantation embryos," published in Nature Medicine, a team from MyOme, Inc., expanded the whole-genome reconstruction (WGR) strategy to predict the risk of common diseases by using parental genome sequencing and embryo genotyping to predict the genomic sequence of the embryo.

The researchers used a combination of molecular biology and statistical methods to link parental chromosomes into "haplotypes," each corresponding to a single haploid chromosome, determine the meiotic recombination site for each embryo, and identify the haplotypes in each embryo. The meiotic recombination loci of each embryo are identified, and related haplotype segments are assembled between each recombination locus to approximate the entire genetic embryonic genome. The results showed a prediction accuracy of approximately 98% when compared to actual births. To explore the accuracy of WGR in predicting risk for common diseases, the researchers used the reconstructed embryonic genome to calculate a polygenic risk score (PRS), which showed an accuracy of approximately 99% for the genotypes of loci associated with the PRS.

In summary, this preclinical study demonstrates the feasibility of the WGR strategy, and the reconstructed results can accurately calculate PRS. Using WGR to calculate PRS for common variants can more accurately predict the risk of many common diseases.

Link to the paper: https://www.nature.com/articles/s41591-022-01735-0

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