XL 22q11 IGL BA consists of an orange-labeled probe hybridizing proximal to the IGL gene region at 22q11.2 and a green-labeled probe hybridizing distal to the IGL gene region at 22q11.2.

Probe maps are created in accordance with the intended purpose of the product. Solid colored bars do not necessarily indicate that the probe fully covers the indicated genomic region. Therefore, caution is advised when interpreting results generated through off-label use. Probe map details based on UCSC Genome Browser GRCh37/hg19. Map components not to scale. Further information is available on request.

The immunoglobulin (IG) genes for the kappa light chain at 2p12 (IGK), the lambda light chain at 22q11 (IGL) and the heavy chain at 14q32 (IGH) are recurrently involved in the development of non-Hodgkin lymphomas (NHL). By far most frequently involved is IGH with more than 30 partner genes, less frequently IGK and IGL. IG-translocations are leading to juxtaposition of proto-oncogenes with IG enhancer sequences resulting in overexpression of the respective oncogene. Chromosomal translocations involving c-MYC at 8q24 and IG genes frequently occur in Burkitt lymphoma (BL). BL is a rare but fast growing type of NHL which is rapidly fatal if left untreated. About 75% of BL patients are carrying the MYC rearrangement t(8;14) while the remainder show a translocation between MYC and IGK or IGL. MYC-IG rearrangements are also involved in other B-cell malignancies such as atypical Burkitt/Burkitt-like lymphoma, diffuse large B-cell lymphoma, follicular lymphoma, mantle cell lymphoma and multiple myeloma. Besides 8q24 (MYC), other translocation partners for IGL, such as chromosomal regions 2p13-14, 3q27 (BCL6), 4q13, 6p25, 16p12, 17p11.2 and 17q21, are known.

FISH break apart assays are valuable tools for the detection of IG light chain rearrangements independent of the translocation partner. Furthermore, double translocations have been described which are difficult to detect by PCR-based methods.

Clinical Applications

• Non-Hodgkin Lymphomas (NHL)

XL 22q11 IGL BA hybridized to normal lymphocytes. Two normal overlapping interphases are shown. The green and orange probes are flanking the IGVL gene region which is relatively large in size. Thus, the distance between the differently labeled signals in normal cells might appear greater than observed with probes flanking smaller genes.

• Martin-Subero et al (2002) Int J Cancer 98:470-474
• Einerson et al (2006) Leukemia 10:1790-1799
• Fujimoto et al (2008) Eur J Haematol 80:143-150