Purpose: To explore a new preimplantation genetic testing (PGT) method for de novo mutations (DNMs) combined with chromosomal balanced translocations by whole-genome sequencing (WGS) using the MGISEQ-2000 sequencer.
Methods: Two families, one with maternal Olmsted syndrome caused by DNM (c.1246C>T) in TRPV3 and a paternal Robertsonian translocation and one with paternal Marfan syndrome caused by DNM (c.4952_4955delAATG) in FBN1 and a maternal reciprocal translocation, underwent PGT for monogenetic disease (PGT-M), chromosomal aneuploidy, and structural rearrangement. WGS of embryos and family members were performed. Bioinformatics analysis based on gradient sequencing depth was performed, and parent-embryo haplotyping was conducted for DNM diagnosis. Sanger sequencing, karyotyping, and chromosomal microarray analysis were performed using an amniotic fluid sample to confirm the PGT results.
Results: After 1 PGT cycle, WGS of 2 embryos from the Olmsted syndrome family revealed euploid embryos without DNMs; after 2 cycles, the 11 embryos from the Marfan syndrome family showed only 1 normal embryo without DNM, copy number variations (CNVs), or aneuploidy. Moreover, 1 blastocyst from the Marfan syndrome family was transferred back to the uterus; the amniocentesis test results were confirmed by PGT and a healthy infant was born.
Conclusions: WGS based on parent-embryo haplotypes was an effective strategy for PGT of DNMs combined with a chromosomal balanced translocation. Our results indicate this is a reliable and effective diagnostic method that is useful for clinical application in PGT of patients with DNMs.
Keywords: Chromosomal balanced translocation; De novo mutation; Preimplantation genetic testing; Whole-genome sequencing.