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The genetic predisposition to type 1 diabetes (DM1) is associated with genes of the human leukocyte antigen (HLA) system, specially the HLA-DR and -DQ. In Caucasians, the HLA-DR3 and -DR4 antigens are associated with susceptibility and the -DR2, with protection. In Brazil, a country with a large miscegenation of European Caucasians, Native Amerindians and African Blacks, the genetic basis of DM1 has not been adequately studied. The aim of this paper is to present a critical review of articles indexed in the MEDLINE and LILACS-BIREME data basis about the association of HLA with DM1 in Brazilians. Eight papers, all of them from the Southeast region, were found. Immunogenetic susceptibility to DM1 in Brazilians was associated with HLA-DRB1*03, -DRB*04, -DQB1*0201, -DQB1*0302 alleles, and protection against DM1 was associated with HLA-DQB1*0602, -DQB1*0301 alleles and -DR2 and -DR7 antigens. Since the Brazilian population is not racially homogeneous, it is not possible to extrapolate studies from a single region to the remainder of the country. It is necessary to study populations from different regions to identify new associations or to strengthen associations with the ones already identified. This knowledge will contribute to future prophylactic or therapeutic interventions in the group of Brazilians at risk of developing DM1.

Genetic, immunological and environmental factors are involved in the pathogenesis of the gastrointestinal diseases. Situated on the short arm of the chromosome 6, the HLA system is very polymorphic and has the capacity to confer susceptibility or resistance to different diseases. The relationship HLA vs. disease differs with the disease and, sometimes, with the ethnic-racial group studied. Histocompatibility molecules could determine the age of onset, the treatment response and the clinical course for some diseases. The recent discovery of new methods to typify HLA alleles and the changes in its nomenclature has contributed to a better understanding of this system. Nevertheless, has not thoroughly widespread. The aim of this review is to discuss the HLA structure and function, methods of detection, nomenclature and its association with celiac disease, Crohn's disease, autoimmune hepatitis, autoimmune pancreatitis and oral recurrent ulcers.

Many studies have been trying to identify genetic markers for ophthalmological diseases, including, among others, the HLA (Human Leukocyte Antigens). Localized on the short arm of chromosome 6, the human leukocyte antigen system is well known for its capacity to confer susceptibility or resistance to different diseases. In view of its accentuated polymorphism, the strength and type of association differs with the disease and sometimes, with the studied ethnic-racial group. The development of molecular methods to typify HLA alleles and recent updates of their nomenclature has contributed to a better understanding of this system. In this review, some aspects of the human leukocyte antigen system are discussed, such as the methods of detection, nomenclature and association with acute anterior uveitis, ocular cicatricial pemphigoid, young-onset keratoconus and birdshot retinochoroidopathy.