Minute chromosomal rearrangements detected prenatally by fluorescence in situ hybridization.

Initial approaches to prenatal diagnosis from fetal karyotyping involved application of standard cytogenetic techniques. However, when fetal samples, such as chorionic villus cells or amniocytes are used, small chromosome rearrangements cannot be easily identified because they lack a distinct banding pattern. We report here two cases with minute chromosome rearrangements detected prenatally by fluorescence in situ hybridization. The use of this technique allowed precise identification of fetal chromosome abnormalities, demonstrating its usefulness for characterizing conditions that would be difficult to diagnose correctly with conventional banding methods alone.