Next-Generation Sequencing-Based Preimplantation Genetic Testing for De Novo NF1 Mutations

Neurofibroma type 1 (NFI) is an autosomal dominant genetic disease associated with cancer and cognitive dysfunction. The 50% de novo mutation rate and numerous mutation types of the NF1 gene pose challenges to preimplantation genetic testing (PGT) for NFI. In 2020, a couple was subjected to next-generation sequencing (NGS)-based PGT at our center. Both husband and wife carried de novo NF1 mutations. Biopsied trophectoderm samples underwent whole-genome amplification using multiple displacement amplification. NGS was conducted to detect NF1 mutations as well as 105 closely linked single-nucleotide polymorphisms (SNPs) flanking NF1. Since no affected family member was available, the affected embryos identified by NF1-targeted sequencing were assigned as probands, based on which a haplotype analysis was constructed with informative SNP sites. Sanger sequencing was administrated for verification. Aneuploidy screening through NGS was performed in the same PGT cycle. Finally, among the nine biopsied blastocysts, two unaffected and euploid blastocysts were obtained in the couple, and one of the blastocysts was transferred in a frozen–thawed embryo transfer (FET) cycle. The outcome of FET is under observation. This study is the first to apply NGS-based PGT for NFI. In cases of sporadic NFI cases without affected family members, NGS-SNP can perform haploid analysis in an accurate manner by assigning the affected embryos as probands.