CHARACTERIZATION OF A COMPLEX TRANSLOCATION [T(4-9-22)(P16-Q34-Q11)] IN CHRONIC MYELOGENOUS LEUKEMIA BY FLUORESCENCE IN-SITU HYBRIDIZATION TECHNIQUE

A patient was referred with a high leukocyte count and diagnosed with chronic myelogenous leukemia (CML). Although practically asymptomatic since the time of diagnosis, he had a variable and inconsistent respon se to treatment. All of his bone marrow cells had a complex, three-way translocation, involving chromosomes 4, 9 and 22. Translocation of ch romosome 4 to chromosome 9 was undetectable by routine cytogenetic tec hniques; however, by the fluorescence in situ hybridization technique, a three-way translocation was identified 46,XY,t(4;9;22)(p16;q34;q11) . Although, other chromosomes are frequently involved in complex or va riant translocations with chromosome 9 and 22, participation of chromo some 4 is a very rare event. So far, two previous cases have been desc ribed in the literature with translocations involving chromosome 4p16. We present a third case of CML having similar break points whose clin ical presentation is unusual.