Deletion 13q in B-CLL: Interphase FISH Reveals More 13q- Than Does CpG Stimulation.

The most common recognized cytogenetic change in B-CLL is a deletion involving band 13q14.3. Dewald found a heterozygous or homozygous 13q– in 92% of CLL patient samples using the FISH probe D13S319 that hybridizes to 13q14.3 (BJH 121:287, 2003). This contrasts with the usually normal conventional chromosome analysis (CCA) results partly because CLL cells divide infrequently but also because the 13q– is often visualized only by FISH (Stockero, Ca Genet Cytogenet 166:152, 2006). Mayr recently showed that CpG stimulation can reveal a chromosomally abnormal CLL clone in metaphase cells (Blood 107:742, 2006). The purpose of the present study was to compare the incidence of microdeletion and visible 13q deletion in CLL using interphase FISH and CCA after CpG culture on the same peripheral blood specimens.