Deletion of 14q24.1∼q24.3 in a patient with acute lymphoblastic leukemia: a hidden chromosomal anomaly detected by array-based comparative genomic hybridization

A 4-year-old patient, who was newly diagnosed with acute lymphoblastic leukemia (ALL), was referred to us for cytogenetic evaluation. He had a normal karyotype by G-banded chromosome analysis, and a deletion of the ETV6 (alias TEL) gene was determined by fluorescence in situ hybridization analysis using DNA probes specific for t(12;21), which leads to ETV6/RUNX1 (alias TEL/AML1) gene fusion, but no translocation was found between the two genes. To find out if there were possibly additional subtle chromosomal changes undetectable by routine cytogenetics, high-density 385 K oligo array comparative genomic hybridization (CGH) assay was performed. Besides the confirmation of the 12 p deletion, a deletion of a 12-megabase (Mb) chromosomal segment on 14q24.1∼q24.3 was also detected. Within the deleted 12-Mb region, there were a total of 155 genes and at least 28 of these were cancer-related genes. A similar approach by array CGH in patients with ALL, especially in those patients with 12 p deletion, could help to determine the significance of this rare event.