Short tandem repeat polymerase chain reaction used in prenatal diagnoses of the zygosity and common chromosomal trisomies in multiple pregnancies

Abstract

To evaluate the value of short tandem repeat polymerase chain reaction (STR-PCR) in identification of zygosity in multiple pregnancy and detection of the common chromosomal trisomies. Amniotic fluid or fetal blood samples were collected from 38 fetuses in 17 multiple pregnant women who had indications for prenatal diagnosis or planed to be performed feticide. Of the 17 cases there were 13 sets of twins (26 fetuses) and 4 sets of triplets (12 fetuses). Parental blood samples were collected. STR-PCR technique was employed to determine the zygosity and detect trisomy 21, trisomy 18, trisomy 13, and trisomy sex chromosomes. Amniotic fluid or blood samples were collected from 18 singleton pregnant fetuses as controls for detecting chromosomal trisomies. All 7 cases with gestation by assisted reproductive techniques were multizygotic. In 7 cases associated with one fetal malformation, only one set of twin was dizygotic. There were no above mentioned trisomies found in the multiple pregnancies while 2 trisomy 21, one trisomy 18 and 13 respectively were detected in the singleton pregnant group. Feticide was performed on 4 multizygotic cases in which 3 were triplets and 1 was twin associated with an abnormal fetus. Following-up showed that there was no any bad effect after procedure. STR-PCR can be used in identifying the zygosity correctly and quickly while being used in detecting chromosomal trisomies. It facilitates monitoring multiple pregnancy as well as selecting appropriate methods of feticide.