The clinical significance of the free light chain and hevylite assays in the diagnostic classification, staging , monitoring and prognostic evaluation of patients with monoclonal gammopathies presenting at SQUH

Monoclonal gammopathies (MGs) are conditions that are characterized by the production of excessive amounts of immunoglobulins produced from a single abnormal clone of a B lymphocyte or a plasma cell that developed from a single pro-B germ cell. MM is an incurable B- cell malignancy characterized by plasma cell infiltration of the bone marrow, organ dysfunction and a monoclonal immunoglobulin (M-protein) in serum, urine or both. . The incidence of MGUS in the United States is around 3.2 % of those who are 50 yrs of age or older and multiple myeloma accounts for around 10 % of all hematological malignancies. The risk of progression from MGUS to MM is about 1 % per year. The burden of disease in Oman is not well documented, however, in 2009, 13 new cases of myeloma were reported. We do not know the real incidence of monoclonal gammopathies in Oman in general . Ethnic variations in the incidence and the severity of monoclonal gammopathies is also well known .Over the last few years, increased understanding in the pathogenesis of monoclonal gammopathies in general and in MM in particular has led to significant advances in the diagnosis and treatment of patients with MM allowing hope in a generally otherwise fatal disease . Several existing and recently evolving biochemical and hematological markers have been used in the diagnosis, management and monitoring of patients with various types of plasma cell dyscrasias, in particular in MGUS and MM. HevyLite TM is a new and recently developed assay that facilitates (via polyclonal antisera) the separate quantification of the kappa and lambda bounded amounts of a given immunoglobulin ( heavy/Light chain HLC, namely : IgG kappa, IgG lambda, IgA kappa, IgA lambda , IgM kappa and IgM lambda individually as well as their relative ratios ( HLC r).This assay has been used successfully in other ethnic populations in the evaluation and prognostic classification of various plasma cell disorders. The purpose of this study is to prospectively evaluate the clinical significance of the free light chain and the new Hevylite assay at diagnosis and in the evaluation of treatment responses in patients with monoclonal gammopathies in general and symptomatic multiple myeloma in particular. Another objective is to systematically characterize patients presenting with monoclonal gammopathies according to their clinical and laboratory findings before and after treatment. Given the above mentioned and well known ethnic disparities in the clinical presentation and prognosis of various monoclonal gammopathies (and their underlying etiologies )and the paucity of information regarding the clinical and laboratory characteristics of patients presenting with plasma cell dyscrasias in the Sultanate and the Arab world as a whole, this study is vital and can serve as a prototype for populations with similar ethnic backgrounds including the Gulf and other Arab countries.