The occurrence of variant Ph translocations in chronic myeloid leukemia (CML): a report of six cases.

Variants of Philadelphia chromosome (Ph) translocation were detected in six of 95 Ph positive chronic myeloid leukemia (CML) patients (6·3 per cent). Two of these patients showed a Ph variant of ‘simple’ type, involving chromosomes 10 and 12. In four patients, the variant Ph was of ‘complex’ type involving a third chromosome:chromosomes 1, 6, 7 and 12 in addition to 9 and 22. Two of these resulted in the occurrence of a ‘masked’ Ph. In addition to variant Ph translocations, variant breakpoints such as q12 (two patients) and q13 (one patient) on chromosome 22 were observed in another three patients with t(9;22).