The origin of deletion 22q11 in chronic lymphocytic leukemia is related to the rearrangement of immunoglobulin lambda light chain locus.

The technology of array comparative genomic hybridization (array-CGH/aCGH) enabled the identification of novel genomic aberrations in chronic lymphocytic leukemia (CLL) including the monoallelic and biallelic deletions affecting 22q11 locus. In contrast to previous publications, we hypothesized that the described 22q11 deletions are a consequence of the rearrangement of immunoglobulin lambda light chain locus (IGL) segments surrounding several protein-coding genes located in this region. Indeed, using array-CGH and PCR analysis we show that all deletions (n=7) affecting the 22q11 locus in our cohort (n=40) are based on the physiological mechanism of IGL rearrangement. This demonstrates that this loss of genetic material is likely not pathogenic and in fact is merely a marker of IGL rearrangement.