PAX5 and cancer: OGM revealed a large deletion of chromosome 9p (p13.3 to p21.3), which encompassed 16,321,476 base pairs and contained 245 genes, including CDKN2A/2B and PAX5. OGM further revealed a smaller deletion of 88,550 base pairs on chromosome 7 involving IKZF1. The large deletion (>16 Mb) identified by OGM may have been missed by karyotyping due to the mosaic nature of the cancer cells (with a deletion heterozygosity of approximately 20%) or their reduced proliferative capacity in standard culture conditions.