FIRST-TRIMESTER PRENATAL-DIAGNOSIS USING TRANSCERVICAL CELLS - AN EVALUATION

Human trophoblastic cells can be retrieved by minimally invasive proce dures from the endocervical canal between between 6 and 15 weeks gesta tion. The incidence with which fetal cells can be detected in transcer vical cell (TCC) samples varies according to the method of collection and the molecular techniques employed for their identification. Fluore scence in-situ hybridization (FISH) and polymerase chain reaction (PCR ) assays have been successfully used to detect aneuploidies and Y-deri ved DNA sequences in TCC samples obtained from male fetuses. Chromosom e specific polymorphic DNA sequences (small tandem repeats) have also been employed to identify, by quantitative fluorescent PCR, fetal cell s in TCC samples. Furthermore, Rh(D) sequences have been amplified in samples retrieved from Rh(D) negative mothers. Preliminary results als o suggest that prenatal diagnoses of thalassaemia and sickle cell anae mia can be performed on clumps of cells isolated from TCC samples. Ove rall systematic studies allow optimism about the possibility of using TCC samples for the prenatal diagnosis of selected inherited disorders .