Spontaneous expression of fra(11)(q23) in a patient with Ewing's sarcoma and t(11;22)(q23;q11).

Cytogenetic analysis of a Ewing's sarcoma revealed a 46,XX,t(8;18)(q11;q21.3), t(11;22)(q23-24;q11-12) chromosome pattern. Observation of t(11;22) is consistent with other reported cases of Ewing's sarcoma. One breakpoint in this translocation, 11q23, coincides with the location of a folate-sensitive fragile site. Examination of peripheral blood leukocyte chromosomes from the patient revealed a 46,XX chromosome pattern with spontaneous, fluorodeoxyuridine-, and Bactrim-induced expression of fra(11)(q23). This may be the first demonstration of constitutional fra(11)(q23) expression in a patient with a neoplasm that exhibits a chromosome rearrangement involving this breakpoint and the first observation of spontaneous expression of this fragile site. These results provide a basis for discussion of the relationship between fragile sites and chromosome rearrangements.