RESUMO
The powerful genetic polymorphism of the HLA system has been used to identify individuals and populations. Ethnic groups may be characterized by specific HLA allele frequencies and particular extended HLA haplotypes; also, genetic relationships among these groups may be deduced. In the present study, serology and DNA typing were used to detect HLA-A, -B, -C, -DR, and -DQ alleles in each individual and to calculate characteristic haplotypes in Algerians. These results were compared to those previously obtained in other populations, particularly northern Mediterraneans; genetic distances and their respective dendrograms place Basques and Spaniards closer to Algerians than to other Europeans. Also, characteristic Basque and/or Spanish haplotypes are found in Algerians; i.e., A30-B18-Cw5-DR3-DQ2 and A1-B57-Cw7-DR7-DQ2. This supports the evidence that the Algerian population, mainly its paleo-North African component (Berbers), has a common descent with Basques and Spaniards, probably reflecting a preneolithic relationship between Iberians and paleo-North Africans.
Assuntos
Frequência do Gene/imunologia , Antígenos HLA/genética , Haplótipos/imunologia , África do Norte/etnologia , Argélia/etnologia , Alelos , População Negra/genética , Antígenos HLA-A/genética , Antígenos HLA-B/genética , Antígenos HLA-DQ/genética , Humanos , Itália/etnologia , Desequilíbrio de Ligação/imunologia , Polimorfismo Genético/imunologia , Espanha/etnologiaRESUMO
It has been established that HLA antigens are susceptibility factors for different cancers, including thyroid tumors. However, the diversity and sometimes weak and contradictory associations found have frequently led to the view that the HLA and tumorigenesis links might be the result of statistical errors. However, it has recently been established that it is indeed a currently complex and unexplained but real phenomenon, which may be crucial in preventing several types of cancer. In the present work we have found in a relatively large series of thyroid cancer patients (n = 161) that both HLA class I (B35) and class II (DR11) antigens are susceptibility factors only in the papillary tumor group of patients, B35 association p value is found at the limit of significance (pc(120) = 0.05); the follicular group did not show any HLA association, suggesting that the etiopathogenesis of each type of cancer is different. HLA-B35 and DR11 are not working together to induce tumorigenesis and each of them seems to confer susceptibility by using different pathways or by being markers of distinct neighboring susceptibility genes. DR4 has also been found in 86% (n = 6) of Hürthle cell carcinoma. No association has been found between HLA and disease activity. HLA mechanisms of association to cancer are discussed and a world-wide HLA/tumorigenic study is proposed to obtain a clear picture of the puzzling and controversial susceptibility markers found in different tumors and in different ethnic groups.
Assuntos
Antígenos de Histocompatibilidade Classe II/análise , Antígenos de Histocompatibilidade Classe I/análise , Neoplasias da Glândula Tireoide/etiologia , Suscetibilidade a Doenças , Antígeno HLA-B35/análise , Antígeno HLA-B35/genética , Antígenos HLA-DR/análise , Antígenos HLA-DR/genética , Subtipos Sorológicos de HLA-DR , Antígenos de Histocompatibilidade Classe I/genética , Antígenos de Histocompatibilidade Classe II/genética , Humanos , Neoplasias da Glândula Tireoide/genética , Neoplasias da Glândula Tireoide/imunologiaRESUMO
A new HLA-DR8 allele (HLA-DRB1*0806) found in the Algerian population is described here. This allele has an exon-2 nucleotide sequence identical to that of the HLA-DRB1*0801 allele, except for a GGT to GTG change in codon 86, yielding an amino acid substitution (glycine to valine). This change is also found in other HLA-DRB1 and HLA-DRB3 evolutionary-related allele pairs. HLA-DRB1*0806 is the most frequent HLA-DR8 allele found in this population (three of eight HLA-DR8-positive individuals) and is included within the HLA-DQA1*0102-DQB1*0602 haplotype (HLA-DQ6 serotype). This combination of HLA-DQ alleles is sporadically found associated with other HLA-DR8 alleles in other ethnic groups, i.e., HLA-DRB1*0804 in Bushmen and in North American blacks and HLA-DRB1*0803 in African blacks. Also, the HLA-DRB1*0806-DQ6 haplotype only bears one HLA-DRB gene copy, a common characteristic of the HLA-DR8 haplotype family. An exon-2 HLA-DR8 dendrogram has also been constructed with the available sequence data, indicating that this new allele does not seem to be placed at a distance significantly different from the origin to that of HLA-DRB1*0804 (proposed to be the eldest in the HLA-DR8 allele diversification pathway). A possible HLA-DR8 evolutive pathway is postulated according to the available exon-2 HLA-DR8 allele sequences.
Assuntos
Alelos , Genes MHC da Classe II , Antígenos HLA-DR/genética , Antígenos de Histocompatibilidade Classe II/genética , Filogenia , Argélia , Sequência de Bases , Éxons , Subtipos Sorológicos de HLA-DR , Cadeias HLA-DRB1 , Humanos , Dados de Sequência Molecular , Grupos Raciais/genética , Alinhamento de Sequência , Homologia de Sequência do Ácido NucleicoRESUMO
A diallelic restriction fragment length polymorphism of the CD3-epsilon (epsilon) gene, which encodes for an invariant component of the human T-lymphocyte receptor, is observed when using genomic DNA TaqI digests probed with a CD3-epsilon chain cDNA probe. This combination shows two alleles of 9.1 kb and 8.4 kb with a frequency of 0.66 and 0.34, respectively, in the Spanish population. None of these alleles is associated with susceptibility to juvenile rheumatoid arthritis (JRA) or insulin-dependent diabetes mellitus (IDDM).