Trophoblast Retrieval and Isolation from the Cervix for Noninvasive, First Trimester, Fetal Gender Determination in a Carrier of Congenital Adrenal Hyperplasia

Congenital adrenal hyperplasia (CAH) is an autosomal recessive defect in cortisol biosynthesis that elevates fetal androgen levels to cause genital ambiguity and external genital masculinization in newborn females. Introducing dexamethasone in utero by 7 weeks gestation precludes virilization of affected females. However, identification of a male fetus prior to week 7 could avert the necessity of steroid treatment in half of pregnancies at risk of CAH. We recently introduced trophoblast retrieval and isolation from the cervix (TRIC), an approach that noninvasively isolate homogeneous trophoblast cells from pregnant women as early as 5 weeks gestation, using a Papanicolaou test. Here, we have used TRIC to correctly identify male fetal DNA when both parents were carriers of the mutation that produces CAH and previously produced an affected child. Trophoblast cells (1400) obtained by TRIC were assessed using immunocytochemistry with an antibody against the trophoblast-specific β subunit of human chorionic go...