ENRICHING AND IDENTYFING FETAL CELLS IN MATERNAL BLOOD FOR IN SITU HYBRIDIZATION

摘要

To provide in situ hybridization assays in which the sex of a fetus, geneticcharacteristics or abnormalities, infectiousagents or identification of other chemical, biochemical or genetic propertiesare detected by nucleic acid hybridization of fetalcells, such fetal cells, which circulate in maternal blood, are enriched,detected and interrogated. The techniques are capable ofdetecting a single genetic abnormality in a single cell, involving as few asapproximately 75 base pairs, by visual microscopicex-amination. Genetic abnormalities may include deletions, additions,amplifications, translocations or rearrangements. Multipleabnormalities may also be detected simultaneously, and they may be visuallydistinguished by color. Cells may be obtained fromamniocentesis, chorionic villi sampling, or in vitro fertilization embryos orproducts of conception, but are preferably frommater-nal peripheral blood. Fetal cells such as lymphocytes, erythrocytes ortrophoblasts may be enriched from maternal blood.Eryth-rocytes may be enriched by removing maternal white blood cells with animmobilized antibody to a cell surface antigen, e.g.CD45. Fetal cells may be enriched by density gradient centrifugation. Fetalcells are desirably distinguished from maternal cellsby staining, e.g. with a labeled antibody to cytokeratin or to fetalhemoglobin of for fetal hemoglobin by hematoxylin/eosin, or byin situ hybridization to detect one or more fetal mRNAs, e.g., fetalhemoglobin or fetoprotein. Kits are provided for the disclosedprocedures.