Childhood acute lymphoblastic leukaemia with ider(21)(q10)t(12;21)(p12;q22): a new recurrent abnormality showing ETV6/CBFA2 fusion

Abstract

The cytogenetically unidentifiable t(12;21) (p12;q22), resulting in ETV6/CBFA2 fusion, is the most frequent chromosomal aberration in childhood acute lymphoblastic leukaemia (ALL). We report a variant, ider(21) (q10)t(12;21)(p12;q22), which was shown to contain double ETV6/CBFA2 fusions by fluorescence in situ hybridization. This is the second case of such an ider(21) in childhood ALL, suggesting that it is a new recurrent abnormality. Since the ider(21) is cytogenetically indistinguishable from i(21)(q10) and idic(21)(p11), changes associated with similar clinical features as the t(12;21), i.e. pre‐B‐cell ALL and age 1–10 years, we suggest that all ALL displaying these changes should be tested for ETV6/CBFA2 fusion transcript.