임산부 말초혈액에서 중합효소연쇄반응 ( PCR ) 을 이용한 태아의 성염색체 분석과 이의 산전유전 진단응용

Abstract

Objectives : Detection of Y-chromosome specific gene in the maternal circulation has clinical importance because of its potential usefulness in determining fetal sex in mothers with severe X-linked disorders such as classic hemophilia A and Duchenne`s muscular dystrophy. Numerous attempts have been made to identify Y specific gene in bloods of mothers bearing male fetuses, however, the results have been controversial. Therefore, we have investigated the use of a nested polymerase chain reaction assay for the detection of a fetal specific Y-chromosome sequence. Methods : Y chromosome specific ZFY gene DNA sequence(using Z1, Z2 and Z3, Z4 primers) and Y chromosome sequence in DYS 14 locus (using Y1.5, Y1.6 and Y1.7, Y1.8 primers) have been identified by an in vitro enzymatic deoxyribonucleic acid amplification method in peripheral blood specimens of 22 pregnant women with gestational ages of 9 to 40 weeks. Results : All women bearing male or female baby were positive for the ZFY gene. Thirteen fetuses were confirmed as males by amniocentesis or chorionic villi sampling, and 10 of these were positive for the Y chromosome specific sequence in DYS 14 locus using Y1.5, Y1.6 and Y1.7, Y1.8 primers(sensitivity 76.9%), however, 4 of the 9 cases diagnosed as females were also positive(specificity 55.5%). Positive and negative predictive values were 71.4% and 62.5%. In terms of the gestational age, positive predictive values of 66.6%, 66.6% and 80% were obtained for the first, second and third trimesters, respectively. The corresponding negative predictive values are 50%, 50%, and 100%, respectively. Conclusion : Fetal sex determination by PCR employing maternal peripheral blood is usually possible in late pregnancy. It is less reliable in early pregnancy. It appears that using a method separating fetal cells from maternal blood and then by running PCR on these cells with Y1.5, Y1.6 and Y1.7, Y1.8 primers could make a fairly accurate fetal sex determination.