Optimized PGT-M Strategy for Patients With No Proband

The clinical practice of PGT-M for monogenetic disease usually adopted a double-checking strategy, which detect the mutation by Sanger sequencing and meantime construct haplotypes using the DNA sample of the proband so as to avoid the risks of misdiagnosis due to recombination and allele drop out (ADO). When there is no affected parent or offspring to serve as the proband, embryo carriers identified through direct mutation detection can be preferentially taken as probands for subsequent linkage analysis. In cases where none of the embryos are detected as mutant carrier, single sperm or the second polar body (PB2) can be complementally collected in the work-up of haplotype establishment. Our study aims to develop an optimized strategy of haplotype construction using gametes or arrested embryos for PGT-M in pedigrees with single gene diseases and no proband in the setting of difficult cases, which takes into account the expected number of oocytes acquired and the gonadal mosaicism.