A large-scale evaluation of amnio-PCR for the rapid prenatal diagnosis of fetal trisomy

Objective Traditional chromosome preparation from amniotic fluid samples of ten involves lengthy culture procedures in order to obtain cells for analys is. Multiplex quantitative fluorescent polymerase chain reaction (PCR) is a new molecular biological technique capable of quantifying in-situ DNA with out the need for cell culture. Our objective was to test the reliability of PCR using fetal DNA from amniotic fluid (amnio-PCR) for the rapid prenatal diagnosis of the common trisomies. Design This was a large prospective study of 5000 amniocentesis specimens. Multiplex quantitative fluorescent PCR was performed specifically for short tandem repeat sequences within chromosomes 21, 18, 13, X and Y. All aminoc entesis samples were subsequently analyzed by traditional karyotyping metho ds. Results Amnio-PCR detected all 89 major autosomal trisomies in this cohort. Diagnosis of sex chromosome anomalies was accurate for cases involving fir st meiotic division nondisjunction. However, further markers were necessary to detect sex chromosome anomalies arising from second meiotic division no ndisjunction, highlighting the importance of using specific markers that en able the quantification of both the X and the Y chromosomes simultaneously. Conclusions Rapid prenatal diagnosis of trisomies 21, 18, and 13 and the se x chromosome anomalies using amnio-P CR is a reliable technique that aids t he clinical management of pregnancy. The speed of the methodology will help to minimize the period of parental anxiety in the wait for a diagnostic te st result.