Acute promyelocytic leukemia (APL) or M3 is a subtype of acute myeloid leukemia, according to the French- American-British group classification. High frequencies of APL have been reported previously by many investigators. We here studied AML patients to determine the frequency of APL in Tabriz in northwest Iran. We reviewed 483 AML patients from 1996-2003. M2 and M3 cases accounted for 43.4% and 19.4% of the total, respectively. Our study thus provides further evidence of high frequencies of APL associated with geographical areas. Further studies should now be performed to evaluate genetic and environmental predisposing factors in Iran.
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