Document Type : Research Articles
Department of Centralised Molecular Diagnostics, Apollo Hospitals, Chennai-6, Tamil Nadu, India.
Department of Haematology, Apollo Hospitals, Chennai-6, Tamil Nadu, India.
Department of Genetics, Dr. ALMPGIBMS, University of Madras, Chennai-113, Tamil Nadu, India.
Objective: Multiple myeloma (MM) is a clinically and genetically heterogeneous plasma cell neoplasm. The
prognosis of MM patients is dependent on several factors including the patient’s age, the stage of disease and genetic
alterations. This study aimed to determine the frequency of common chromosomal abnormalities and their significance in
MM patients referred to a tertiary healthcare center in India. Methods: Fluorescence in situ hybridization on interphase
nuclei from bone marrow cells using seven MM-specific probes for recurrent aberrations was performed in a total of
215 newly diagnosed patients. Results: Chromosomal abnormalities were detected in 161 (74.9%) MM patients in
this study. The most frequent aberration was trisomy(ies) involving only gain of chromosomes in 48 (22.3%) cases.
A translocation involving the IGH gene alone or accompanied by trisomy(ies) or by monosomy 13/13q deletion or by
both was registered in 80 (37.2%) patients. Atypical patterns such as a deletion of the IGH variable segment (IGHv)
on the derivative chromosome 14 or on the native (normal) chromosome 14, biallelic deletion of IGHv, deletion of
the IGH constant segment on the rearranged chromosome14 and extra fusions were noticed in 21 (9.8%) patients
with an IGH rearrangement. Monosomy 13/deletion 13q was identified singly or as part of a complex karyotype in
74 patients (34.4%). Clonal heterogeneity and additional abnormalities including TP53 deletion and monosomies of
chromosomes 4, 9, 14 and 16 were recorded in 18.6% and 16.3% of patients respectively. Patients with abnormalities
exhibited plasmacytosis, reduced hemoglobin value and high level of ß2-microglobulin. Conclusions: A lower median
age and a low frequency of IGH translocations particularly t(11;14) and chromosome 13 abnormalities suggest ethnic
diversity. Further investigations on genetic alterations including IGH deletions will contribute to improved insights
into the biology of myeloma disease, risk stratification and patient management.