RAPID DETECTION OF TRISOMY-21 BY HOMOLOGOUS GENE QUANTITATIVE PCR (HGQ-PCR)

Down's syndrome results from the production of three copies of chromos ome 21 within a cell. We have devised a method termed the homologous g ene quantitative polymerase chain reaction (HGQ-PCR), which uses one p air of primers and which can directly identify the additional copy of chromosome 21 by simultaneously amplifying two highly homologous genes of the human liver-type phosphofructokinase located on chromosome 21 (PFKL-CH21) and the human muscle-type phosphofructokinase located on c hromosome 1 (PFKM-CH1) for self-detecting determination. On analysis o f 34 cases of Down's syndrome, including two cases of unbalanced trans location 46, XY, der (14; 21) (q10; q10), +21, and 100 normal individu als, the relative ratio of the PFKM-CH1/PFKL-CH21 product was 1.33 +/- 0.323 (mean +/- SD) and 0.40 +/- 0.16 (mean +/- SD) for disomy DNA an d trisomy DNA, respectively. The difference between these two groups w as highly significant (P < 0.001). These results indicate that this qu antitative method is practical and may be used for the prenatal diagno sis of Down's syndrome caused by trisomy 21.