The t (7;17) translocation resulting in fusion of the JAZF1 gene (on chromosome 7p15) to the SUZ12 gene (on 17q21) represents the most common chromosomal rearrangement in low-grade endometrial stromal tumors, being detected in approximately 30% of low-grade ESS and 50% of endometrial stromal nodules tested [4, 5]. The gene discussed is JAZF1; the disease is endometrial stromal tumor.