Mannose binding protein genetic polymorphisms associated with decreased protein are found more frequently in african american sle patients compared to a control population

Mannose Binding Protein (MBP) is a member of the complement system which functions in both the classical and alternative pathways. Multiple structural and promoter polymorphisms have been identified, some of which are associated with lower circulating levels of MBP. We determined the gene frequency of polymorphic variants at two structural sites and two promoter sites in an African American systemic lupus erythematosus (SLE) population and an African American control population. Each of the polymorphic variants associated with decreased serum levels of MBP was found independently to be more frequent in the SLE population compared to the control population. The 230A polymorphism has a gene frequency of .163 in the SLE population compared to .089 in the control population (p=.0273). The 239A polymorphism has a gene frequency of .120 in the SLE population compared to .047 in the control population (p=.0101). The -221C polymorphism has a gene frequency of .25 in the SLE population and .147 in the control population (p-.0443). The promoter polymorphism, -550C, is associated with the highest levels of circulating MBP, and it is negatively associated with an increased risk of SLE (p=.007). Therefore, each of the MBP polymorphisms associated with decreased serum levels is found with increased frequency in African American SLE patients compared to controls suggesting that it represents another example of a complement deficiency associated with SLE.