RESUMO
<p><b>OBJECTIVE</b>To establish a multiplex real-time quantitative PCR method for diagnosis of Down's and Edward's syndrome.</p><p><b>METHODS</b>The sequences of the amyloid precursor protein gene (APP) in the Down's region of chromosome 21 and the thymidylate synthetase gene (TYMS) on chromosome 18 were co-amplified in the same tube. The relative quantitative index DeltaCT value was used to differentiate Down's and Edward's syndrome patient from healthy individual. Four groups of samples, including 36 blood samples from normal controls (group A), 15 amniotic fluid samples from normal pregnancies (group B), 21 samples from patients with Down's syndrome (group C) and 6 samples from patients with Edward's syndrome (group D), were investigated in the study.</p><p><b>RESULTS</b>The mean DeltaCT values of the four groups were -0.48+/-0.15, -0.49+/-0.12, -1.26+/-0.17 and 0.25+/-0.12 respectively. The DeltaCT value from group B was not different from that from group A (P>0.05). However, the DeltaCT values from group C and group D were significantly different from that from group A (P<0.01), and no overlapping was observed.</p><p><b>CONCLUSION</b>The DeltaCT values from multiplex real-time quantitative PCR could be used to rapidly diagnose Down's and Edward's syndrome simultaneously.</p>