Epidemiology of monoclonal gammopathy in Morocco - A hospital-based study

Background: Monoclonal gammopathies are a group of disorders associated with clonal proliferation of plasma cells that produces a monoclonal protein.

Aims: The main objective of this study was to describe the epidemiological and immunochemical characteristics of monoclonal gammopathies diagnosed during 19 years in a Moroccan teaching hospital.

Materials and results: This retrospective study enrolled 443 Moroccan patients with monoclonal gammopathy, patients meeting the inclusion and exclusion criteria in at the biochemistry department of Military Hospital in Rabat, the capital of Morocco, from January 2000 to August 2019. Of the 443 enrolled patients, 320 (72.23%) were men and 123 (27.77%) were women. All patients were of Caucasian origin, from 12 Moroccan regions. The patient's samples were collected and subjected to serum protein electrophoresis and serum immunofixation electrophoresis to further characterize the monoclonal protein. The mean ± SD age of the 443 participants was 62.24 ± 13.14 years. Reasons for being admitted to the hospital were as follows, bone pain (41.60%), renal failure (19.08%), alteration of the general condition (12.21%), and anemia (10.69). Plasma cell proliferative disorders in our study were as follows, multiple myeloma (MM) (45.65%), Monoclonal gammopathies of undetermined significance (MGUS) (39.05%), Waldenstrom's macroglobulinemia (5.58%), Lymphoma (2.27% + 1.2%), Chronic Lymphocytic Leukemia (2.48%), Plasma cell leukemia (1.86%), Plasmacytoma (0.62%), POEMS syndrome (0.41%), and Amyloidosis (0.84%). The most frequent isotypes in MM were the IgGκ (62) 36.5%, IgGλ (52) 30.6%, IgAκ (27) 15.9%, and the IgAλ (19) 11.2%. It is also worth noting that Free light chain MM represents 20% of all cases of MM.

Conclusions: We found that monoclonal gammopathies are age-related and affects men more than women, also the results of this study point to the delayed diagnosis of monoclonal gammopathies, since most of our patients were diagnosed at the MM stage. The most frequent isotypes were the IgGκ and IgGλ in MM and MGUS, in Waldenström macroglobulinemia were IgMκ and IgMλ and the oligoclonal profile represented only 3.70%.