Duplication of the Band q21q27 on the Long Arm of Chromosome 3: A Rare Cytogenetic Event in B-Chronic Lymphocytic Leukemia (B-CLL).

Objectives: We present the case of an 83-year-old female with a long history of B-CLL followed by observation only. Twelve years after her diagnosis of CLL, routine follow-up chromosome analysis of peripheral blood revealed an abnormal metaphase with a dup(3)(q21q27) in 18 of 20 metaphase cells. To further characterize the abnormal chromosome 3, fluorescence in situ hybridization (FISH) was performed using the Abbott BCL6 probe for 3q27. An additional BCL6 signal was observed in 303 of the 500 interphase nuclei examined. The ISCN was reported as 46,XX,dup(3)(q21q27)[1]/46,XX[2]. nuc ish(5'BCL6, 3'BCL6)x3(5'BCL6 with 3'BCL6x3)[303/500]. This abnormality was seen again in one of three available metaphases in a follow-up peripheral blood study five years later, consistent with persistent disease. Molecular genetic analysis identified the presence of somatic hypermutation of the immunoglobulin heavy chain gene variable region (IGH-V), which is recognized as an independent favorable prognostic marker in CLL. FISH analysis was negative for loss of SEC63 (6q21), amplification of MYC (8q24), loss of ATM (11q22.3), trisomy 12, loss of D13S319 (13q14.3), loss of TP53 (17p13.1) and CCND1/MYEOV IGH rearrangement [t(11;14)(q13;q32.30)]. Partial trisomy 3 is a relatively rare event seen in B-CLL, with commonly overrepresented segments including the q21-23 region and the q25-29 region of the long arm of chromosome 3, as well as changes leading to gains of 3q26- q27. The clinical significance of this finding in B-CLL is uncertain; however, our patient remains well and has not required therapy 17 years after her initial diagnosis.