REARRANGEMENTS OF IMMUNOGLOBULIN AND T CELLRECEPTOR a AND y GENES ARE ASSOCIATED WITHTERMINAL DEOXYNUCLEOTIDYL TRANSFERASEEXPRESSION IN ACUTE MYELOID LEUKEMIA

In the classification of acute leukemias, the nuclear enzyme terminal deoxynucleotidyl transferase (TdT)' is a marker commonly used to differentiate between the lymphoid or myeloid origin of the neoplastic clone. Common, T, and null acute lymphoblastilc leukemias (ALL) are characteristically TdT''', reflecting the proliferation of immature lymphoid cells, while TdT is usually negative in acute myeloid leukemia (AML). However, it is well documented that a small proportion (5-10%) of AML are TdT' (l, 2). The explanation for this unexpected, though consistent finding, has remained uncertai