TNF and mantle cell lymphoma: Some examples of polymorphisms identified in patients with MCL include (1) a homozygous polymorphism in intron 2 of TNF-β, (2) a single base pair substitution at position -308 in the promoter for TNF-α, and (3) a single G-to-C base pair substitution at position -174 in the promoter for IL-6 (Blackwell, 1999; Sakthianandeswaren et al., 2009).