Two-colour FISH detection of the inv(16) in interphase nuclei of patients with acute myeloid leukaemia.

The inv(16)(p13q22) and t(16;16)(p13;q22) in acute myeloid leukaemia are associated with a relatively good prognosis but are difficult to detect using classic cytogenetics. We have designed a two-colour fluorescence in situ hybridization approach that uses two DNA probes that map close to and on either side of the inv(16) p-arm breakpoint region. This new strategy clearly detected the inv(16)(p13q22)/t(16;16)(p13;q22) on both metaphase chromosomes and in interphase nuclei, even when they are of poor quality. This procedure also detected the inv(16) in cases with an additional deletion of sequences proximal to the 16p-arm breakpoint which is present in 20% of all cases.