Mannose-binding lectin (MBL) is a collagen-like serum protein that mediates activation of the complement system and is of importance for host defence. Common variant alleles situated both in the promoter and structural region of the human MBL gene (MBL2) influence the stability and the serum concentration of the protein. Epidemiological studies have suggested that genetically determined variation in MBL serum concentration influences the susceptibility to and the course of different types of infections, autoimmune, metabolic and cardiovascular diseases, but this is still a subject of debate. The fact that these genetic variations are very frequent indicates a dual role for MBL in host defence. In this survey, we summarize the current molecular understanding of human MBL genetics.

We have analized the combination of variants at 4 sites of the gene MBL (mannose binding lectin) which is part of the immune system, in 19 normal individuals from the islands of Anapia-Suana in the Lake Titicaca. OnIy 3 combinations (haplotypes) were registered: LYPB, HYPA and LYPA; the proportion of the pressumed defective haplotype LYPB is 0.58 being the highest ever recorded. This haplotype is rare among European, Asian and African populations. It predisposes to infectious diseases as tuberculosis and AIDS as well as autoimmune diseases like reumatoid arthritis and lupus erithematosumo This finding lead our future efforts to elucidate the reason of this high frequency of LYPB and to determine its proportion in other islands of the Titicaca Lake.

Mannose-binding lectin (MBL) is one of the five recognition molecules in the lectin complement pathway. Common variant alleles in the promoter and structural regions of the human MBL gene (MBL2) influence the stability and serum concentration of the protein. Epidemiological studies have shown that MBL2 variant alleles are associated with susceptibility to and the course of different types of infectious and inflammatory conditions. However, it has been suggested that these alleles are maintained in different populations due to selected advantages for carriers. We investigated the MBL2 allelic variation in indigenous individuals from 12 different West Central South America localities spanning from the desert coast, high altitude Andean plates and the Amazon tropical forest within the territories of Peru (n = 249) (Departments of Loreto, Ucayali, Lambayeque, Junin, Ayacucho, Huancayo and Pu...