From them, 15 were excluded for the following reasons: three articles were duplicates;37-39 two did not report usable data;40,41 and 10 investigated other polymorphisms of TNF-α rather than TNF-α-308.5,42-50 Finally, twenty-one case-control studies, which comprised 2880 MS cases and 3579 controls, were included in the study.12-32 The selected characteristics of the 21 case-control studies included in this meta-analysis are summarized in table 1 (figure 1). The gene discussed is TNF; the disease is myeloid sarcoma.