The test and the Technology

SafeT21Express  was invented by a research team from the Chinese University of Hong Kong after the discovery of the presence of fetal DNA in maternal plasma and serum in 1997. The detection of fetal chromosomal aneuploidies including Down Syndrome (T21), Edwards Syndrome (T18), Patau Syndrome (T13), Sex Chromosome Aneuploidies and microdeletion/microduplication all in ONE test is now made possible.

SafeT21Express  adopts the patented Non-invasive Prenatal Testing (NIPT) technology which reduces the use of conventional invasive diagnostic test such as amniocentesis and chorionic-villus sampling by almost 30%, and thereby avoids the risks associated with those invasive procedures.

SafeT21Express     utilizes Next Generation Sequencing followed by bioinformatics analysis on both maternal DNA and cell free placental DNA found in maternal blood. The results are generated by comparing the allelic ratios of the amplified fragments derived from the targeted chromosome of both mother and fetus. If the fetus is aneuploid, allelic ratios on the aneuploid chromosome are skewed in comparison with other, non-aneuploid chromosomes.



  • YM, Lo et al. 1997, ‘Presence of fetal DNA in maternal plasma and serum’, The Lancet, 350;485-487
  • YM, Chan et al. 2015, ‘Women's uptake of non-invasive DNA testing following a high-risk screening test for trisomy 21 within a publicly funded healthcare system: findings from a retrospective review.’, Prenat diagn., 35(4):342-347
  • DW, Bianchi et al. 2018, ‘Sequencing of Circulating Cell-free DNA during Pregnancy’, N Engl J Med, 379:464-473