Detection of subtle reciprocal translocations by fluorescence in situ hybridization.

Three different subtle reciprocal translocations were detected on long, well-banded chromosomes. The same translocations were examined using fluorescence in situ hybridization (FISH) with chromosome-specific libraries and unique DNA sequences. Our findings show that FISH allows rapid and unequivocal detection and characterization of this type of chromosome rearrangement. This approach is especially useful for prenatal diagnosis when one of the parents is a balanced carrier of such small fragment translocations.