MBL2 and immunodeficiency disease: MBL is an important acute-phase serum protein involved in the innate immune response that can trigger complement activation (Wong et al., 1999), and an association between allele ∗B in the exon 1 of the MBL2 gene has been reported with the occurrence of immunodeficiency and chronic infectious diseases (Turner, 2003; Vallinoto et al., 2006).