Two of the hottest fields in the genomic diagnostics market are NIPT (Noninvasive Prenatal Testing) and liquid biopsy. Both share the same mechanism by testing the circulating free DNA in the bloodstream even though NIPT applies in the pregnancy diagnostics while Liquid Biopsy is for cancer.In the case of NIPT, the fetus sheds DNA into the mother's bloodstream and the testing can thus detect if the fetus has genetic disorders by drawing blood from the mother. Unlike the invasive amniocentesis that does present a low risk of miscarriage, NIPT is completely safe in this regard while being noninvasive. The most common chromosomal disorders NIPT covers are Trisomy 21 (Down syndrome), Trisomy 18 (Edwards syndrome), and Trisomy 13 (Patau syndrome). However, NIPT is not 100% accurate and can only be a screening test at this point. The American College of Obstetricians and Gynecologists (ACOG) asks for more studies to be done before it can recommend NIPT to the screening for all pregnancies.
Cancer cells shed DNA molecules into the patient bloodstream and like NIPT the cancer's condition can be determined by testing these circulating tumor DNA (ctDNA), thus the term liquid biopsy. It is noninvasive because the biopsy is not done at the site of the tumor. There are also circulating tumor cells (CTCs) from the tumor into the bloodstream, so liquid biopsy can be a test for either ctDNA or CTCs. In addition to being a diagnostic test, liquid biopsy can be used to monitor the tumor situation during the treatment.
Next-Generation Sequencing (NGS) technology has been the major player in both NIPT and liquid biopsy. In NIPT, fetal and maternal DNA are sequenced, then either a counting method or a SNP based method is employed to identify any chromosomal aneuploidy. Liquid biopsy can be used to detect copy number aberrations or single nucleotide variants (SNVs). Because of the mixture of different DNA molecules and the small amount of fetal or tumor DNA, scientists are still facing the challenge to achieve accurate diagnostic results. With more research and technologies in these fields, it is simply a matter of time for NIPT and liquid biopsy to become routine diagnostic procedures.