Fluorescent in situ hybridization for the diagnosis of genetic disease at postnatal, prenatal, and preimplantation stages.

Publisher Summary Fluorescent in situ hybridization (FISH) has become one of the most powerful techniques in modem genetic research. It is principally a tool for assigning particular nucleic acid clones (“probes”) to chromosome preparations in order to map those clones to a particular chromosome region, but it has proved to be a very powerful diagnostic technique also. The chapter focuses on the role of FISH for the diagnosis of genetic disease at postnatal, prenatal, and preimplantation stages. FISH has allowed cytogenetic analysis of metaphases that are difficult (or impossible) to analyze because of poor chromosome preparations or when the chromosome anomaly is too complex or too small to see with classic chromosome banding techniques. Cytogenetic diagnosis following birth is particularly useful in deciding upon future treatment of an affected individual. Often a rapid cytogenetic diagnosis can be essential in deciding upon immediate treatment for a newborn child or indeed upon whether to sustain life at all. It is in prenatal diagnosis that there has been the most interest in diagnostic cytogenetics. Amniocentesis and/or chorionic villus sampling (CVS) in the first or second trimester of pregnancy reveals the chromosomal constitution of the unborn fetus and allows the family to decide (under genetic counseling) whether to continue with the pregnancy or to terminate it if the fetus is affected. Preimplantation diagnosis (PID) is carried out on an embryo prior to implantation into the mother's uterus. The chapter highlights how major advances in this field have been used in diagnostic situations.