Analysis of monoallelic FLT3 deletions.

Interphase nuclei from the patient with loss of the wild-type allele were studied by FISH using BAC clone RP11-179F17 (green). Cohybridization with a probe recognizing a genomic region at chromosome band 7q35 (red) was performed to monitor hybridization efficiency. All 7 nuclei exhibit 2 green and 2 red fluorescence signals, indicating that no monoallelic FLT3 deletion occurred in this patient. Identical results were obtained with BAC clone RP11-9D14 (not shown). Original magnification × 100.