Down syndrome (trisomy 21), which has an incidence of 1 in 800 live births, is considered to be the most frequent etiology of mental retardation and it is the predominant reason for women seeking prenatal diagnosis. Trisomy 21 is used as a benchmark because it is the most common aneuploidy compatible with life and is associated with mental retardation and serious congenital anomalies. Currently used screening tests for aneuploidy are based on the assessment of fetal sonographic markers and/or the evaluation of biochemical markers in the maternal circulation during the first and second trimester.

Screening test based on the combination of nuchal translucency assessment and biochemical markers at 11+0-13+6 weeks of gestation may detect 90-94% of pregnancies affected by Down syndrome at a false positive rate of 5%. The current gold standard for diagnosis of trisomy 21 is provided by invasive sampling of fetal genetic material through chorionic villus sampling (CVS) or amniocentesis followed by conventional cytogenetic or DNA analysis; however, both procedures are associated with an increased risk of fetal loss of about 1% and therefore they are recommended for pregnancies considered to be at high risk of fetal
trisomy 21.

To minimize the risk of fetal loss and false positive cases, Tri-Gene test is designed for the early prenatal detection of fetal trisomies of 21, 18, 13 and cases of other chromosomal aneuploidies. The non-invasive test carries no risk of causing miscarriage and intrauterine infection, and is highly sensitive with accuracy over 99%.