t(7;12)(q36;p13) and t(7;12)(q32;p13) - translocations involving ETV6 in children 18 months of age or younger with myeloid disorders

Our retrospective karyotype review revealed two rare recurrent translocatio ns affecting ETV6 (TEL): t(7;12)(q36;p13) and t(7;12)(q32;p13). Five patien ts with a 1(7;12) were from a group of 125 successfully karyotyped pediatri c patients enrolled in consecutive clinical AML trials of the Dutch Childho od Leukemia Study Group over a period of 7 years. During a search of availa ble cytogenetic databases, we found 7q and 12p abnormalities in two additio nal Dutch patients and in three participants in Pediatric Oncology Group tr ials. A del(12p) had been initially identified in four of these patients an d re-examination of the original karyograms revealed a t(7;12)(q36;p13) in two instances and a probable 1(7;12) in the other two. FISH confirmed the p resence of a t(7;12)(q36;p13) in the latter. Most (n = 7) also had trisomy 19. The t(7;12)(q36;p13) (n = 9) was more com mon than the t(7;12)(q32;p13) (n = 1). These subtle translocations were found only in children 18 months of age or younger. A literature search revealed that the 1(7;12) with brea kpoints at 7q31-q36 and 12p12-p13 had been reported in six children with my eloid disorders and in two with acute lymphoblastic leukemia; all were 12 m onths of age or younger. Only two of the 17 for whom survival data were ava ilable, were alive after at least 22 months of continuous complete remissio n. Our findings suggest that ETV6 rearrangements due to a t(7;12) may play an adverse role in myeloid disorders in children 18 months of age or younge r. Therefore, children in this age group with myeloid disorders should be s creened for both MLL and ETV6 rearrangements.