OBJECTIVE: To block the transmission of Cranio-facial-nasal syndrome (CFNS) caused by a large deletion of the EFNB1 gene through preimplantation genetic testing for monogenic disorders (PGT-M). METHODS: A patient with craniofacial deformities and his parents who had visited Shiyan People's Hospital in June 2020 were selected as the study subjects. The child underwent whole exome sequencing (WES) and qPCR validation. After genetic counseling, PGT-M was chosen for the reproductive blockage. This study was approved by the Ethics Committee of the Hospital (Ethics No.: sysrmyy-087). RESULTS: The child was diagnosed with CFNS due to a heterozygous deletion of exons 1-5 of the EFNB1 gene through WES and qPCR, which showed a X-linked dominant inheritance. The mother underwent ovarian stimulation with a modified PPOS protocol, which has yielded 11 oocytes. After ICSI fertilization, 4 blastocysts were formed, and MALBAC whole genome amplification was performed on the trophoblast biopsy cells, and SNP haplotypes of the family members and embryos were analyzed to indirectly determine the presence of maternal pathogenic haplotypes. Chromosomal copy number variation analysis was conducted through next-generation sequencing to screen for euploid embryos, resulting in the identification of two euploid embryos that did not carry the mutation of the EFNB1 gene. The first transfer was unsuccessful, but after adjusting the transfer timing through endometrial receptivity assessment (ERA), clinical pregnancy was achieved. Prenatal diagnosis at 19 weeks excluded the EFNB1 gene exons 1-5 deletion in the fetus. A healthy girl was delivered by Cesarean section at 38⁺⁶ weeks, and Q-PCR confirmed she has no aforementioned EFNB1 gene deletion. CONCLUSION This study has successfully blocked the transmission of CFNS caused by a large deletion of the EFNB1 gene (exons 1-5) using a PGT-M strategy, which may provide reference for the intervention of similar genomic variations that cannot be directly detected.
Humans ; Female ; Male ; Craniofacial Abnormalities/diagnosis* ; Ephrin-B1/genetics* ; Polymorphism, Single Nucleotide/genetics* ; Preimplantation Diagnosis/methods* ; Pedigree ; Asian People/genetics* ; Craniosynostoses/genetics* ; Pregnancy ; Gene Deletion ; Sequence Deletion ; Genetic Testing/methods* ; Adult ; East Asian People