Kinship analysis on single cells after whole genome amplification

Abstract

Short Tandem Repeat (STR-) and Single Nucleotide Polymorphism (SNP-) genotyping have been extensively studied within forensic kinship analysis. Nevertheless, no results have been reported on kinship analysis after whole genome amplification (WGA) of single cells. This WGA step is a necessary procedure in several applications, such as cell-based non-invasive prenatal testing (cbNIPT) and preimplantation genetic diagnosis (PGD). In cbNIPT, all putative fetal cells must be discriminated from maternal cells after enrichment from whole blood. This study investigates the efficacy and evidential value of STR- and SNP-genotyping methods for the discrimination of 24 single cells after WGA, within three families. Formaldehyde-fixed and unfixed cells are assessed in offspring-parent duos and offspring-mother-father trios. Results demonstrate that both genotyping methods can be used in all tested conditions and scenarios with 100% sensitivity and 100% specificity, with a similar evidential value for fixed and unfixed cells. Moreover, sequence-based SNP-genotyping results in a higher evidential value than length-based STR-genotyping after WGA, which is not observed using high-quality offspring bulk DNA samples. Finally, it is also demonstrated that the availability of the DNA genotypes of both parents strongly increases the evidential value of the results.