ABSTRACT
A case of Down's syndrome in which transient myeloproliferative disorder developed is described. In hematologic findings of peripheral blood, high blast cell count on 1st day of birth had been found and after serial follow-up for several weeks, decrease in WBC counts from 22.6x10(9)/L to 7.5x10(9)/L and blast cell counts from 31% to 2% occurred. The karyotype of his patient was 45,XY, der (13;14) (q10;q10), der(14;21) (q10;q10), +21. Karyotyping of his father revealed 45,XY, der(13;14) (q10;q10). Without specific chemotherapy, hematologic and clinical recovery was occurred within several weeks. We deport a case of transient myeloproliferative disorder in Robertsonian translocatlon type of Down's syndrome accompanying another Robertsonian translocation, der (13;14) (q10;q10), inherited from his father.