Fluorescence In Situ hybridization with X and Y chromosome probes for cytogenetic studies on bone marrow cells after opposite sex transplantation

We investigated the efficacy of fluorescence-labelled chromosome probes (CEP-X/Y) for the X and Y chromosomes to study patients who have had opposite sex BMT. These probes hybridize to the centromere region of the X chromosome and nearly the entire long arm of the Y chromosome. These probes are direct-labelled and produce X and Y signals that can be simultaneously viewed and readily distinguished from each other by color and size after only five brief washes. We investigated BM specimens from 20 normal donors and 16 patients who had undergone an opposite sex BMT. We found no significant interinvestigator differences with respect to scoring XX or XY interphase cells. The 'normal range' for XX cells in males was up to 0.628% and for XY cells in females it was up to 0.299%. Each of the specimens from the patients who underwent BMT had a significant number of donor cells compared with normal range. We suggest that an economical, rapid and accurate cytogenetic test can be achieved by using these probes as an adjunct to conventional cytogenetics.