A RELIABLE METHOD FOR OBTAINING HIGH-RESOLUTION BANDED CHROMOSOME PREPARATIONS FROM CHORIONIC VILLUS SAMPLES

A reliable method for obtaining high-resolution banded chromosome preparations from chorionic villus samples (CVS) is described, in which a synchronization cell-culture technique with the use of thymidine is introduced. After culturing a suspensin of chorionic villus cells in a medium supplemented with 0.3 mg/ml thymidine for 13-17 hr, cells were washed twice, and recultured for further 8 hr. The cells were then treated with 10 μg/ml ethidium bromide or 1 μg/ml actinomycin D for 1 hr and subsequently with 0.01 μg/ml Colcemid for 30 min. The average mitotic index obtained was more than 60 mitoses/mg CVS, and more than 60% of mitoses proceeded to the prometaphase stage, the later prophase stage, or in between. The application of this method for prenatal diagnoses in five CVS in the first trimester pregnancies proved that it is a simple, practical and efficient prenatal diagnostic method. © 1990 The Japan Society of Human Genetics.