The most frequent chromosomal abnormality in CLL is deletion of 13q14, being monoallelic in 76% of cases, and biallelic in 24% [13, 14, 24]. This deletion, also detected in MBL [11] occurs at a much lower frequency in multiple myeloma, DLBCL, mature T-cell lymphomas, and in several solid tumors [25-29]. A minimal deleted region (MDR) has been defined in a large number of CLL cases with monoallelic 13q14 deletion. This region contains the long non-coding RNA deleted in leukemia (DLEU)-2, and the first exon of the DLEU1 gene [30, 31]. Two microRNAs (miR-15a and miR-16-1) were present within intron.
