Prenatal fetal sex determination from maternal peripheral blood using polymerase chain reaction

We have investigated the use of a nested polymerase chain reaction(PCR) assay with Y-specific sequence from the DYS 14 locus on the short arm of Y-chromosome for prenatal sex determination in the peripheral blood of 22 pregnant women who participated in the antenatal genetic diagnosis program. The sensitivity and specificity of the nested PCR using DYS 14 locus primers(Y_1.5,Y_1.6, and Y_1.7,Y_1.8) were 76.4% and 55.5%, respectively. In terms of gestational age, positive predictive values of 66.6% , 66.6% , and 80% were obtained for the first, second, and third trimester respectively. The corresponding negative predictive values were 50% , 50% , and 100% respectively. Male specific band was positive in three of the six cases of female bearing women and male specific band was negative in three of the seven cases of male bearing women during 9-16 gestational weeks showing low sensitivity. But all cases except one show the male specific band during the male fetus and all female fetuses did not show the male specific 198 base pair band during 18 approximately 40 gestational weeks. This study suggests that prenatal sex determination by PCR employing maternal peripheral blood was usually possible in late pregnancy but less reliable in early pregnancy. It seems that if we used a method separating fetal cells from maternal blood and then run PCR on these cells with DYS 14 locus primers we could make a fairly accurate fetal sex determination.