Analysis of BIRC3 disruption in patients with chronic lymphocytic leukemia: association with complex karyotypes and TP53 deletion

ANDREA KRZYWINSKI; GISELDA DE STEFANO ; DIEGO FERNÁNDEZ; IRMA SLAVUTSKY; CAMILA GALVANO; MARÍA SILVANA CUGLIARI; MARCELA MIODOSKY; MARTA ZERGA; CARMEN STANGANELLI; L MELILLO; R PENALBA

Edinburgh

Workshop; International Workshop on Chronic lymphocytic leukemia; 2019

International Workshop on Chronic lymphocytic leukemia

The deletion within de long arm of the chromosome 11 is a recurrent karyotypic aberration in chronic lymphocytic leukemia (CLL), identified in approximately 10%-20% of all CLL patients, associated with bulky lymphoadenopathy and adverse outcome. This alteration may be variable in size and showed a certain degree of prognostic heterogeneity. The minimal deleted region on 11q always includes ATM (ataxia telangiectasia mutated) gen (11q22.3) but can also encompass BIRC3 (Baculoviral IAP repeat containing 3) (11q22.2), located ~6Mb centromeric to ATM, a negative regulator of non-canonical NF-kB signaling pathway. BIRC3 lesions are rarely detected in CLL at diagnosis (4% of patients), but are observed in 24% of fludarabine-refractory patients. The aim of this study was to evaluate BIRC3 deletions in CLL patients with del11q in order to have a better delineation of this region. Results were correlated with cytogenetic, FISH and IGHV (immunoglobulin heavy chain variable region) mutational status.From a total of 190 CLL patients cytogenetically and FISH (Fluorescence in situ hybridization) studied in our Laboratory between 2015 and 2019, 21 cases (11%) showed deletion 11q (del11q) (12 males and 9 females; mean age: 71.1 years, range: 54-86 years; Rai stages: 0: 7.7%, I-II: 38.5%, III-IV: 53.8%). Chromosome analysis was performed on stimulated peripheral blood lymphocytes cultures. FISH analysis was performed using the CLL panel as well as ODF11q18q (BIRC3/MALT1) DNA probes according to manufacturer´s protocol (Live-Lexel, Argentina). For each probe, two hundred interphase nuclei were analyzed. The cut-offs for positive values were: 3%, 10%, 7.5%, 5,5% and 5.5% for trisomy 12, deletions of D13S319, ATM, TP53 and BIRC3, respectively. BIRC3 mutations was analyzed by PCR with gDNA using primers that amplify exons 7 to 10 of the BIRC3 gene and the intron-exon limits (Haematologica 2015; 100: e237-9), followed by bidirectional sequencing. IGHV (immunoglobulin heavy chain variable region) mutational status was analyzed by RT-PCR and bi-directional sequencing as previously described (Clin Lymphoma Myeloma Leuk 2013; 13:447-57). IGHV sequences with