Method of real time detecting No.21 human chromosome number by quantitative PCR technology

A method for detecting the number of human chromosomes NO.21 by real-time quantitative PCR technique in order to diagnoise the triple-21 syndrome includes such steps as using the genome-specific single-cope sequence as the molecular marker of chromosome, choosing part of non-polymorphic fragments of DSCR4 gene as target molecular marker, choosing part of fragments of RABIF gene as internal reference molecular marker, designing two pairs of primers and relative Taqman probes, amplifying said two sequences in a single tube by PCR, determining the relative value deltact, and determining the number of chromosomes No.21.