RAPID MOLECULAR METHOD FOR PRENATAL DETECTION OF DOWNS-SYNDROME

We have evaluated a rapid method that allows prenatal detection of Dow n's syndrome in less than 24 hours. DNA from uncultured amniotic fluid , fetal blood, and tissue samples was amplified with the small tandem repeat (STR) marker D21S11. Quantitative analysis of fluorescent STR p roducts with evaluation of their sizes provided clear evidence for tri somy 21. Whilst most normal samples showed two amplification peaks of equal size, Down's syndrome samples were characterised by either th re e STR peaks or two peaks with a ratio of 2:1. Co-amplification with a non-polymorphic sequence allowed analysis of Samples that were homozyg ous for the 21-derived STRs.