RARA and acute promyelocytic leukemia: About 90% to 95% of cases have t(15; 17)(q22; q21), and produces the PML-RARα fusion gene, whose sensitivity to treatment with all-trans retinoic acid (ATRA) and arsenic trioxide makes it the best curable subtype of AML.[1] PML-RARα fusion gene is a marker of APL.