DELETIONS OF CDKN1B AND ETV6 IN ACUTE MYELOID-LEUKEMIA AND MYELODYSPLASTIC SYNDROMES WITHOUT CYTOGENETIC EVIDENCE OF 12P ABNORMALITIES

Seventy-nine acute myeloid leukemias (AML) and myelodysplastic syndrom es without cytogenetic evidence of 12p aberrations were investigated b y fluorescence in situ hybridization with probes for ETV6 and CDKNIB ( previously called TEL and KIPI, respectively) to ascertain whether abn ormalities of these genes are frequently undetected by standard chromo some banding analyses and, if so, whether they are associated with spe cific karyotypic patterns and morphologic features. One of sixty cytog enetically aberrant myeloid malignancies, an AML with a complex karyot ype including del(5q) and del(20q), showed a hemizygous interstitial d eletion of the ETV6 and CDKNIB loci. No concomitant rearrangement of t he other ETV6 allele was detected. Two of nineteen cytogenetically nor mal AML displayed a hemizygous interstitial deletion involving CDKNIB, but not ETV6. Thus, cryptic deletions of these genes seem to be rare in cytogenetically abnormal myeloid malignancies without 12p aberratio ns (2%), whereas they may be more frequent in karyotypically normal AM L (10%). Furthermore, the present findings show that the deletions may be narrow, not including the EN6 gene, and indirectly suggest that CD KNIB, or a closely located genomic segment, is the target of 12p delet ions. (C) 1997 Wiley-Liss, Inc.