Genomic arrays in chronic lymphocytic leukemia routine clinical practice: are we ready to substitute conventional cytogenetics and fluorescence in situ hybridization techniques?

Abstract

Chronic lymphocytic leukemia (CLL) is characterized by a highly variable clinical course. Del(11q) and del(17p), routinely studied by conventional G-banding cytogenetics (CGC) and fluorescence in situ hybridization (FISH), have been related to progression and shorter overall survival. Recently, array-based karyotyping has gained acceptance as a high-resolution new tool for detecting genomic imbalances. The aim of the present study was to compare genomic arrays with CGC and FISH to ascertain whether the current techniques could be substituted in routine procedures. We analyzed 70 patients with CLL using the Cytogenetics Whole-Genome 2.7M Array and CytoScan HD Array (Affymetrix), CGC and FISH with the classical CLL panel. Whereas 31.4% and 68.6% of patients presented abnormalities when studied by CGC and FISH, respectively, these rates increased when arrays were also analyzed (78.6% and 80%). Although abnormality detection is higher when arrays are applied, one case with del(11q) and three with del(17p) were missed by genomic arrays due to their limited sensitivity. We consider that the complete substitution of CGC and FISH by genomic arrays in routine laboratories could negatively affect the management of some patients harboring 11q or 17p deletions. In conclusion, genomic arrays are valid to detect known and novel genomic imbalances in CLL, but should be maintained as a complementary tool to the current techniques.

Keywords::

• Chronic lymphocytic leukemia
• FISH
• conventional G-banding cytogenetics
• genomic arrays

Potential conflict of interest

Disclosure forms provided by the authors are available with the full text of this article at www.informahealthcare.com/lal.

This work has been supported by the following grants: FI10/00625 and PI11/01621 from Fondo de Investigación Sanitaria (FIS), Instituto de Salud Carlos III, Spanish Ministry of Economy and Competitivity, RD07/0020/2004 from Red Temática de Investigación Cooperativa en Cáncer (RTICC), RD09/0076/00036, FEDER, 2009/SGR541 from Generalitat de Catalunya and “Xarxa de Bancs de Tumors” sponsored by Pla Director d’Oncologia de Catalunya (XBTC).