Background: Noninvasive prenatal testing (NIPT) based on cell-free DNA (cfDNA) is widely used. However, biomimetic quality control materials that have properties identical to clinical samples and that are applicable to a wide range of methodologies are still not available to support assay development, internal quality control, and proficiency testing.
Methods: We developed a set of dual enzyme-digested NIPT quality control materials (DENQCMs) that comprise simulated human plasma and mixtures of mother cell line-derived cfDNA based on DNA fragmentation factor digestion (D-cfDNA) and the matched child cell line-derived cfDNA based on micrococcal nuclease digestion (M-cfDNA). Serially diluted samples positive for trisomies 21, 18, and 13 were included in the materials. To evaluate the biomimetics, DENQCMs were analyzed using random massively parallel sequencing (MPS), targeted MPS, and imaging single DNA molecule methods, and the estimated fetal fractions (FFs) were compared with expected FFs. Genome-wide analysis of cfDNA fragmentation patterns was performed to confirm their biological characteristics.
Results: The genetic status of each DENQCM was correctly detected by 4 routine NIPT assays for the samples with FFs >5%. The chromosome Y-based and single-nucleotide polymorphism-based estimations of FFs were linearly related to those expected FFs. The MPS results exhibited a concordance of quality metrics between DENQCMs and maternal plasma, such as GC contents of cfDNA and unique read ratios.
Conclusions: The DENQCMs are universally applicable for different platforms. We propose DENQCMs as an approach to produce matched maternal and fetal cfDNA that will be suitable for the preparation of quality control materials for NIPT.
© 2019 American Association for Clinical Chemistry.