Figure 1.

Diversity of TNFRSF13B in host response to environmental challenges. TNFRSF13B encodes a receptor (TACI) through to support the maturation of B cells, yet the gene is among the most polymorphic in the genome and polymorphism is maintained across mammalian species. The authors speculate that polymorphism of TNFRSF13B reflects balancing selection—balancing benefits and disadvantages of signals the receptor delivers but also manifold intermediate functions the protein and its neighbors in cell membrane confer. The figure depicts two hypothetically distinct regions of the protein that confer phenotypically distinct properties. The balancing of complex sets of phenotypic properties that presumably impact all mammals could underlie extraordinary diversity of the gene across species. CVID, Common Variable Immunodeficiency.