APCAD Part 2: A Novel Method for Detection of Meiotic Aneuploidy in Preimplantation Embryos

Background/Objectives: Preimplantation genetic testing methods to detect aneuploidy (PGT-A) based on genomewide single nucleotide polymorphism (SNP) data were scarce and did not meet our needs. Methods: Hence, we developed a novel method for this purpose. After the raw B-allele frequency (rBAF) values of Single Nucleotide Polymorfisms (SNPs) are obtained from a sample of interest with SNP array, the BAF values for specific categories of SNPs (cBAF) are visualized separately. Results: The analysis of the cBAF, rBAF and Log₂R profiles enables to distinguish all common types of chromosomal abnormalities without haplotyping. This was demonstrated by reanalyzing data from 359 embryos which had previously been analyzed with Karyomapping. We identified additional underrepresented maternal haplotypes in five samples that we could not detect with Karyomapping. In addition, we identified all chromosomes with meiotic-origin copy number gains (both parental homolog (BPH)) (n = 70) and all chromosomes with a non-mosaic copy number loss larger than 5 Mb (n = 93) that had been detected with Karyomapping. Conclusions: We conclude that the proposed method can be used to reliably detect meiotic-origin aneuploidy without haplotyping and, hence without the need for a phasing reference.