OBJECTIVE: To assess the value of single sperm sequencing in preimplantation genetic testing for monogenic disease (PGT-M). METHODS: A Chinese couple with two children whom had died of Spinal muscular atrophy (SMA) and attended the Jiangxi Provincial Maternal and Child Health Care Hospital in June 2020 was selected as the subject. Eleven single sperm samples were isolated by mechanical immobilization and subjected to whole genome amplification. Real-time PCR and Sanger sequencing were used to detect the SMN1 variants in the single sperm samples. Genomic DNA of the wife, her parents and the husband, as well as one single sperm sample harboring the SMN1 variant and two single sperm samples without the variant were used for the linkage analysis. Targeted capture and high-throughput sequencing were carried out to test 100 single nucleotide polymorphisms distributed within 2 Mb up- and downstream the variant site. The haplotypes linked with the SMN1 variants were determined by linkage analysis. Blastocyst embryos were harvested after fertilizing by intracytoplasmic sperm injection. Cells from the trophoblasts of each embryo were biopsied and subjected to whole genome amplification and targeted capture and high-throughput sequencing to determine their carrier status. Chromosomal aneuploidy of wild-type embryos was excluded. An euploid embryo of high quality was transferred. Amniotic fluid sample was taken at 18 weeks of gestation to confirm the status of the fetus. RESULTS: Genetic testing showed that the couple both had deletion of exons 7 ~ 8 of the SMN1 gene. The wife has inherited the deletion from her father, while the husband was de novo. The haplotypes of the husband were successfully constructed by single sperm sequencing. Preimplantation genetic testing has indicated that 5 embryos had harbored the heterozygous variant, 4 embryos were of the wild type, among which 3 were euploid. Prenatal diagnosis during the second trimester of pregnancy has confirmed that the fetus did not carry the deletion. CONCLUSION By single sperm sequencing and PGT-M, the birth of further affected child has been successfully avoided.
Humans ; Pregnancy ; Female ; Child ; Male ; Preimplantation Diagnosis ; East Asian People ; Semen ; Genetic Testing ; Muscular Atrophy, Spinal/genetics* ; Aneuploidy ; Blastocyst/pathology* ; High-Throughput Nucleotide Sequencing ; Spermatozoa

Objective:To explore the value of polar body sequencing in preimplantation genetic testing (PGT) for monogenic disease of a female patient with Van der Woude syndrome.Methods:PGT based on polar body sequencing was performed for a female patient with Van der Woude syndrome caused by a de novoIRF6 pathogenic variant. Totally six oocytes were fertilized by intracytoplasmic sperm injection (ICSI). The first, second polar bodies and the trophoblast ectoderm cells of blastocysts were biopsied respectively. Sanger sequencing was used to detect the pathogenic variant in the biopsied cells after genome-wide amplification. The genotypes and pathogenic possibilities of the embryos were inferred according to the genotypes of corresponding tested polar bodies. In order to prevent the absence of transplantable embryos due to the failure of blastocyst culture, vitrification was performed on an embryo with good morphology and low pathogenic possibility before blastocyst formation. The 175 single nucleotide polymorphisms (SNPs) within the 1M region upstream and downstream from the pathogenic variant location were tested by targeted capture sequencing in the couple and selected polar bodies and embryos to construct the haplotypes. An embryo with low pathogenic possibility was transferred. Prenatal diagnosis was strongly recommended after successful pregnancy. Prenatal and postnatal follow-up were performed. Results:Totally six first polar bodies and six second polar bodies were obtained. The pathogenic variant was successfully sequenced in 11 polar bodies. Among the six embryos, one embryo with low pathogenic possibility was vitrified on day 4 (D4) after fully informed consent of the couple; one embryo developed to blastocyst was detected with high pathogenic possibility; the other four embryos were degenerated during blastocyst culture. The SNP haplotypes closely linked to the pathogenic variant location were successfully constructed by linkage analysis. The haplotype analysis of the embryos was in consistent with Sanger sequencing. The D4 embryo with low pathogenic possibility was transferred. The couple refused to conduct invasive prenatal diagnosis after pregnancy. None orofacial clefts were detected after the baby was born, and the pathogenic variant was not detected in the neonatal cord blood either.Conclusion:This study successfully blocked a female patient with Van der Woude syndrome caused by a de novoIRF6 pathogenic variant give birth to an affected baby by polar body sequencing based preimplantation genetic testing for monogenic disease.

Objective:To explore the value of polar body sequencing in preimplantation genetic testing (PGT) for monogenic disease of a female patient with Van der Woude syndrome.Methods:PGT based on polar body sequencing was performed for a female patient with Van der Woude syndrome caused by a de novoIRF6 pathogenic variant. Totally six oocytes were fertilized by intracytoplasmic sperm injection (ICSI). The first, second polar bodies and the trophoblast ectoderm cells of blastocysts were biopsied respectively. Sanger sequencing was used to detect the pathogenic variant in the biopsied cells after genome-wide amplification. The genotypes and pathogenic possibilities of the embryos were inferred according to the genotypes of corresponding tested polar bodies. In order to prevent the absence of transplantable embryos due to the failure of blastocyst culture, vitrification was performed on an embryo with good morphology and low pathogenic possibility before blastocyst formation. The 175 single nucleotide polymorphisms (SNPs) within the 1M region upstream and downstream from the pathogenic variant location were tested by targeted capture sequencing in the couple and selected polar bodies and embryos to construct the haplotypes. An embryo with low pathogenic possibility was transferred. Prenatal diagnosis was strongly recommended after successful pregnancy. Prenatal and postnatal follow-up were performed. Results:Totally six first polar bodies and six second polar bodies were obtained. The pathogenic variant was successfully sequenced in 11 polar bodies. Among the six embryos, one embryo with low pathogenic possibility was vitrified on day 4 (D4) after fully informed consent of the couple; one embryo developed to blastocyst was detected with high pathogenic possibility; the other four embryos were degenerated during blastocyst culture. The SNP haplotypes closely linked to the pathogenic variant location were successfully constructed by linkage analysis. The haplotype analysis of the embryos was in consistent with Sanger sequencing. The D4 embryo with low pathogenic possibility was transferred. The couple refused to conduct invasive prenatal diagnosis after pregnancy. None orofacial clefts were detected after the baby was born, and the pathogenic variant was not detected in the neonatal cord blood either.Conclusion:This study successfully blocked a female patient with Van der Woude syndrome caused by a de novoIRF6 pathogenic variant give birth to an affected baby by polar body sequencing based preimplantation genetic testing for monogenic disease.