Gac Med Mex
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Comparative Study
[High- and low-risk molecular sequences in autoimmune diseases. An analysis of type I diabetes in Latin America].
Type I diabetes is an autoimmune and a polygenic disease, in which MHC-class II genes contribute to 48% of the disease. The aim of the present study, is to provide a guideline to understanding the molecular association of these genes, through the immunogenetic analysis of 3 Latin american mestizo populations. We included 606 individuals, 349 patients with DMDI and 257 healthy controls coming from 3 geographical areas: Mexico City, Mexico; Caracas, Venezuela and Medellin, Colombia. ⋯ It was demonstrated that the relevant sequences for IDDM expression are located to DRB1 and DQB1 loci with a minimal contribution of DQA1 residues. The sequences determining peptide recognition and the induction of TH1 cells mediating the cellular autoimmune response are in positions DRB1-57 and 74 (an aspartic acid and a glutamic acid respectively, confer protection), modulated by D-57 in the DQ, 8 chain. These data show that DRB1-DQB1 haplotypes are central for IDDM expression and open new pathways for the disease management.
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Parasite diseases such as Leishmaniases and American Trypanosomiases have been increasingly important in Mexico and other countries of the American Region. In known areas, these diseases are highly endemic, and in recently opened developing areas became a new threat to public health. Some social groups working in natural resources exploitation, agriculture, animal stock and public labor are particularly affected. ⋯ Clinical and epidemiological aspects of American trypanosomiasis infections and Chagas's disease and of cutaneous, mucocutaneous, disseminated and visceral leishmaniases, as well as genetic susceptibility studies have been initiated by Mexican scientists. In order to organize and coordinate the molecular epidemiology activities and support effective prevention and control programs against these diseases, political decision from the health, and academic authorities is urgently needed to adopt and support the research strategy for typing Trypanosoma and Leishmania species through exposition and biological markers (analysis of chromosomal DNA, ribosomal genes restriction patterns, DNA sequence, and DNA plasmids); the study of the membrane proteins and isoenzymes and monoclonal antibodies; detecting antigens and nucleic acids; defining susceptibility to infection with genetic markers, and searching for species, variants and mutant strains responsible for high virulence. The support for the establishment of a Reference Center for identification, cryopreservation and registration of parasites, vectors and reservoires is of paramount importance.