DEVELOPMENT OF NONINVASIVE FETAL DNA DIAGNOSIS FROM MATERNAL BLOOD

Several attempts have been made to detect and retrieve fetal nucleated cells including nucleated erythrocytes (NRBCs), leukocytes, and troph oblasts in maternal blood. We have recently developed a new method for non-invasive fetal DNA diagnosis from maternal blood. Peripheral bloo d granulocytes including NRBCs were isolated by a discontinuous densit y gradient method using Percoll (Pharmasia). NRBCs were found and retr ieved at a single cell level using a micromanipulator under a microsco pe. To determine whether the origin of the NRBCs was maternal or fetal , the NRBCs were analysed by polymerase chain reaction (PCR) amplifica tion to determine the presence of a Y-chromosome-specific repeat seque nce in mothers carrying male fetuses. We were successful in predicting fetal sex accurately in 10 out of 11 samples taken from maternal bloo d. This new technique opens up fetal DNA diagnosis from maternal blood during the first trimester of pregnancy to the whole population becau se there is no risk to the fetus or the mother.