Ficolin B is the designation in mouse and rat of a protein also known as L-ficolin, ficolin-2, collagen/fibrinogen domain-containing protein 2, serum lectin p35, EBP-37 or hucolin. Ficolin B is a 313 amino acid member of the ficolin lectin family. It is a secreted innate immunity pattern recognition molecule expressed in liver and plasma that forms a disulfide-linked homopolymer. This extensive N-terminal disulfide bridge formation can lead to a functional dodecamer polypeptide. Ficolin B binds to DNA ligands expressed by late apoptotic and necrotic cells to increase attachment and engulfment. Variation in ficolin B concentrations amongst individuals is associated with polymorphisms in the promoter and structural portion of the FCN2 gene. In patients with Beh鏴t's disease (BD), there exists a significant difference in allele frequency for FCN2 gene single nucleotide polymorphisms (SNPs) within the -557 and -64 promoter sites within HLA-B51 positive and HLA-B51 negative subgroups.