Molecular Cytogenetic Aberrations in Tunisian Patients with Multiple Myeloma Identified by cIg-FISH in Fixed Bone Marrow Cells

Abstract

Cytogenetic studies in multiple myeloma (MM) are hampered by the hypo-proliferative nature of plasma cells. In order to circumvent this problem, we have used a combination of immunolabeling of cytoplasmic Ig light chains (λ or ĸ) and FISH (cIg-FISH), which allowed a comprehensive detection of the most common and/or recurrent molecular cytogenetic aberrations on fixed bone marrow cells of 70 Tunisian patients. Translocations involving the chromosome 14q32 region were observed in 32 cases (45.7%), including 18 cases with a t(11;14), 8 cases with a t(4;14), and 2 cases with a t(14;16). Deletions of the 13q14 region (D13S319/RB1) were detected in 18.6%, and deletions of the 17p13 region (TP53) in 5.7% of the cases, respectively. Of all patients with a D13S319/RB1 deletion, 61.5% also carried a 14q32 translocation, whereas TP53 deletions were associated with a t(11;14) in 2 cases (50%) and a D13S319 deletion in 1 case (25%). Our results suggest that there is a correlation between the presence of 14q32 translocations and chromosome 13q14 deletions in MM patients and that cIg-FISH is more sensitive as compared to conventional karyotyping in detecting molecular cytogenetic abnormalities in this disease.

Multiple myelomda kromozomal aberasyonlar: klinik sonuçlar ve bortezomib’ e yanıt

“…Deletion of 17p13 involving the p53 gene is reported in 5-30% of cases 2,3,[13][14][15] . The 17p13 deletion cannot be detected in MGUS; lower rates are observed in newly diagnosed or early-stage disease, while higher rates are observed in advanced-stage disease.…”

“…The 40.9% rate observed in our study is consistent with previous reports 18,19 . Recent studies have concluded that RB1 region probes are more informative and sensitive in detecting 13q14 deletions 2,20,21 . In our study, the del(13q14) deletion was accompanied by other chromosomal aberrations in 82.3% (28/34) of the patients.…”

Routine laboratory diagnosis of chromosome aberrations in multiple myeloma

“…Another clg-FISH protocol uses fixed cell pellets. 43,44 The advantage of this technique is that cell pellets from conventional cytogenetics can be used for clg-FISH as well. To prevent the cells from aggregating and clumping, the cells were washed in 100% methanol (instead of 96% ethanol), dropped onto slides, followed by adding gently 96% ethanol.…”