Fetal cell recycling: Diagnosis of gender and RhD genotype in the same fetal cell retrieved from maternal blood

OBJECTIVE: Our aim was to develop a new technique, which we have termed fet al cell recycling, that combines the 2 powerful methods of fluorescence in situ hybridization and polymerase chain reaction to maximize the genetic in formation available from a small number of fetal nucleated erythrocytes obt ained noninvasively from the blood of pregnant women. STUDY DESIGN: Blood samples were obtained from 4 Rh-negative women after el ective termination of pregnancy at 7 to 17 weeks' gestation. Fetal nucleate d erythrocytes were separated by flow sorting with antibody to the gamma ch ain of fetal hemoglobin. Fluorescence in situ hybridization with chromosome -specific probes was used to diagnose fetal gender. After fluorescence in s itu hybridization analysis the fetal nucleated erythrocytes were recycled b y a micromanipulation technique and deoxyribonucleic acid diagnosis was per formed with polymerase chain reaction amplification of the RhD gene. RESULTS: Among the 4 case patients we detected a total of 101 fetal nucleat ed erythrocytes. All targeted cells were successfully retrieved with a micr omanipulator. In each case we successfully performed both fluorescence in s itu hybridization and polymerase chain reaction analysis. The predicted fet al gender and Rh status corresponded to the results obtained from fetal tis sue. CONCLUSIONS: Fetal cell recycling combines the powers of highly sensitive m olecular methods to maximize the genetic information available from a singl e fetal cell. This technique will permit noninvasive diagnosis of recessive ly inherited single-gene disorders.