DETECTION of CHROMOSOMAL 14q32 ABNORMALITIES IN B-CELL CHRONIC LYMPHOCYTIC LEUKEMIA.

Conventional cytogenetic and FISH studies with the standard panel (13q14, 11q22.3, 17p13, 12, 6q23) are used to detect chromosomal abnormalities of clinical significance in patients with chronic lymphocytic leukemia (B-CLL). Recently, translocations and 5'IGH deletions involving chromosome14q32 are associated with B-CLL.

Our aim was to investigate the presence and the characteristics of chromosome 14q32 aberrations in a group of patients with B-CLL.

A total of 58 patients with B-CLL were investigated by conventional cytogenetic, in addition the cultures were stimulated with CpG oligodeoxynucleotide plus IL2. FISH studies with 14q32/IGH break-apart probe designed to detect chromosomal breakage of the IGH (14q32) locus, were done for 59 patients.

Chromosomal abnormalities were detected in 60.3% of cases by cytogenetic. 14 patients showed complex cariotype while trisomy 12 was the most frequent anomaly found in 8 patients. Among the twelve other patients several chromosomal aberrations were noted: del(13)(q14), del(13)(q12q21),

del(13)(q12q14), del(13)(q13q32), +21, t(11;13)(q23;q14), +12 t(1;4)(q31;p14), t(3;14)(p21;q22), del (11)(q12) +21, del(6)(q21), inv3(?p13q21), del(11)(q12). Abnormalities of chromosome 14 were found in 23.8% of patients. Deletion of 5'IGH, corresponding to the variable IGH segment, was the most frequent anomaly found in 8 patients. Interesting, a 3'IGH deletion was detected in two patients, while only one patient showed a complete deletion of chromosome 14 (47,XXY,add14q32). Three patients showed 14q32 translocations involving the IGH locus.

Based on our findings, deletions of the variable region of the IGH gene (IGHv) and 14q32/IGH translocations are involved in B-CLL. As these preliminary data are based on small sample size, our goal will be to study the cytogenetic profile of a large number of CLL patients. Future studies will permit the identification of 14q32 translocations and the type and the frequency of IGH rearrangements. Finally, chromosome 14 abnormalities will be correlated to other cytogenetic and FISH abnormalities, and associations with known prognostic markers, such as IGVH mutation status and ZAP-70 expression, will be investigated.

No relevant conflicts of interest to declare.