A novel t(6;14)(q25∼q27;q32) in acute myelocytic leukemia involves the BCL11B gene

Cytogenetic studies in a patient with acute myelocytic leukemia (AML) revealed as the sole karyotypic alteration a half-cryptic rearrangement, identified with 48-color combined binary ratio-labeled fluorescence in situ hybridization (pq-COBRA-FISH) as a reciprocal t(6;14)(q?;q?). The breakpoints were later assigned on the basis of G-banding to t(6;14)(q25∼q26;q32). FISH experiments using genomic probes showed that the breakpoint on 14q32.2 was within bacterial artificial chromosome RP11-782I5 and revealed BCL11B as the only candidate gene in the region. BCL11B is a homolog to BCL11A (2p13), a highly conserved gene implicated in mouse and human leukemias. To our knowledge, this is the first report implicating BCL11B in hematological malignancies. Because of lack of material, the translocation partner remains unknown

Rubinstein-Taybi syndrome caused by submicroscopic deletions within 16p13.3

The Rubinstein-Taybi syndrome (RTS) is a well-defined complex of congenital malformations characterized by facial abnormalities, broad thumbs and big toes, and mental retardation. The breakpoint of two distinct reciprocal translocations occurring in patients with a clinical diagnosis of RTS was located to the same interval on chromosome 16, between the cosmids N2 and RT1, in band 16p13.3. By using two-color fluorescence in situ hybridization, the signal from RT1 was found to be missing from one chromosome 16 in 6 of 24 patients with RTS. The parents of five of these patients did not show a deletion of RT1, indicating a de novo rearrangement. RTS is caused by submicroscopic interstitial deletions within 16pl3.3 in approximately 25% of the patients. The detection of microdeletions will allow the objective confirmation of the clinical diagnosis in new patients and provides an excellent tool for the isolation of the gene causally related to the syndrome