Fetal cells in maternal blood:: The use of primed in situ (PRINS) labelling technique for fetal cell detection and sex assessment

Prenatal diagnosis is presently performed following invasive procedures with variable risks of fetal loss; non-invasive procedures using fetal cells in maternal blood would be welcome for the early detection of fetal sex or aneuploidy. We describe a simple and rapid protocol to detect fetal cells and thus to assess fetal sex. In a first step, nucleated blood cells were separated into mononuclear and polynuclear cells using a double density gradient centrifugation. In a second step primed in situ (PRINS) labelling technique was performed to label Y-chromosomes. 15 samples were studied and correct gender assignment was made in 13/15. The number of labelled nuclei was higher in polynuclear cell phases than in mononuclear cell phases. Moreover, the polylobular aspect of labelled nuclei from polynuclear cell phases strongly suggested that they could belong to fetal polynuclear cells. The PRINS technique combines some advantages of FISH, such as visual assessment of iii situ chromosome labelling and the powerful specificity and sensitivity of PCR. In association with a simple enrichment procedure it constitutes a rapid protocol for fetal cell detection, non-invasive early prenatal sex assessment, and could further be applied to detect the main viable aneuploidies. (C) 1998 John Wiley & Sons, Ltd.