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

OBJECTIVE: To explore the clinical feature and genetic etiology of a patient with Craniofacial nasal syndrome (CNFS). METHODS: A patient with CNFS who had presented at the Guiyang Maternal and Child Health Care Hospital on November 13, 2021 was selected as the study subject. Clinical data of the patient were collected. Peripheral venous blood samples were collected from the patient and her parents and subjected to trio-whole exome sequencing (trio-WES). Candidate variants were verified by Sanger sequencing and bioinformatic analysis. RESULTS: The patient, a 15-year-old female, had predominantly featured forehead bulging, hypertelorism, wide nasal dorsum and bifid nasal tip. Genetic testing revealed that she has harbored a heterozygous missense c.473T>C (p.M158T) variant of the EFNB1 gene, which was detected in either of her parents. By bioinformatic analysis, the variant has not been recorded in the HGMD and ClinVar databases, and no population frequency was recorded in the 1000 Genomes, ExAC, gnomAD and Shenzhou Genome Data Cloud databases. As predicted by the REVEL online software, the variant can confer deleterious effects on the gene or its product. Analysis using UGENE software showed the corresponding amino acid to be highly conserved among various species. Analysis with AlphaFold2 software suggested that the variant may affect the 3D structure and function of the Ephrin-B1 protein. Based on the American College of Medical Genetics and Genomics (ACMG) standards and guidelines and recommendation of Clinical Genome Resource (ClinGen), the variant was rated as pathogenic. CONCLUSION Combining the patient's clinical features and genetic finding, the diagnosis of CNFS was confirmed. The heterozygous c.473T>C (p.M158T) missense variant of the EFNB1 gene probably underlay the disease in this patient. Above finding has provided a basis for the genetic counseling and prenatal diagnosis for her family.
Humans ; Child ; Female ; Pregnancy ; Adolescent ; Ephrin-B1/genetics* ; China ; Computational Biology ; Family ; Mutation