Table 2.
Some distinctive and common qualities in the comparison of fetal cell and cell free DNA based prenatal testing.
| Question | DNA Source | Distinctive Qualities | Common Qualities |
|---|---|---|---|
| What are the instrument needs? | Fetal Cells | Cell sorting Microscopes Cell culture (?) CGH-SNP Platform |
PCR related NextGen Sequencing |
| Fetal Cell-Free DNA | DNA isolation Mass spectrometer |
||
| What are the advantageous capabilities? | Fetal Cells | Potential to be a diagnostic test and not limited to screening Direct analysis of single (?) or pooled (?) cells using biological measurements Amenable to FISH and/or qfPCR analyses for rapid analysis of aneuploidy Capacity for single gene analysis, variation screening or sequencing Potential for functional and polygenic analyses Amenable to CNV (copy number variation) determinations by CGH-SNP analysis |
Non-invasive Capacity for both aneuploidy and CNV analyses |
| Fetal Cell-Free DNA | Preparation more rapid than cells Minimal problems in transporting blood from clinic to centralized labs Potential for CNV determinations by deep sequencing and analysis |
||
| What are the apparent disadvantages or important challenges to be met? | Fetal Cells | Isolation of cells may be labor intensive; cost effective throughput has not been demonstrated Integrity of DNA in possibly apoptotic cells may dictate consistency and quantity of cells required for reliable evaluations Requires faithful and complete amplification of DNA Likely to be few cells analyzed from a sample and thus less likely to be representative of a mosaic condition Stability and integrity maintenance requirements for transport of cells from phlebotomist to laboratory |
Requisite equipment and expertise may limit distribution beyond centralized laboratories |
| Fetal Cell-Free DNA | Becoming validated as an effective diagnostic as well as screening test Accuracy seems to depend on level of proportion of extracted DNA derived from fetus Results are based on (powerful) statistical methods rather than direct biological measurements Unable to determine mosaicism if present Degree of extension of analyses beyond aneuploidy yet to be determined and validated |