Haplotype Construction Using Embryos as Probands of the Pathogenic Variations in EXT1, CUL3, and HBA

Preimplantation genetic testing (PGT) represents a crucial strategy in the prevention of monogenic disorders, ensuring that only embryos free from these genetic conditions are implanted during assisted reproductive technologies. By analyzing the type of haplotypes of the variation of the probands or the carriers, we can significantly enhance the diagnostic precision of PGT. We presented a clinical strategy that uses embryos as probands to construct haplotypes; this innovative approach has successfully delineated the haplotypes associated with pathogenic variations in key genes, such as HBA (encoding hemoglobin subunit alpha), EXT1 (involved in exostoses), and CUL3 (a gene related to various developmental disorders). Ten embryos in three families were tested, all are diagnosed whether with the deletion variations or not by haplotype construction, Sanger sequencing, or PCR. Importantly, we compared SNP results with haplotype analysis by pedigree linkage or long reading sequence. This method can be considered when family members are incomplete and haplotype construction is otherwise unfeasible other than long reading sequencing.