RESUMO
Abstract: Background: Alopecia areata (AA) is a common disorder of unknown etiology that affects approximately 0.7% to 3.8% of patients among the general population. Currently, genetic and autoimmune factors are emphasized as etiopathogenic. Studies linking Human Leukocyte Antigens (HLA) to AA have suggested that immunogenetic factors may play a role in the disease's onset/development. Objectives: To investigate an association between AA and HLA class I/II in white Brazilians. Methods: Patients and control groups comprised 33 and 112 individuals, respectively. DNA extraction was performed by column method with BioPur kit. Allele's classification was undertaken using the PCR-SSO technique. HLA frequencies were obtained through direct counting and subjected to comparison by means of the chi-square test. Results: Most patients were aged over 16, with no familial history, and developed partial AA, with no recurrent episodes. Patients showed a higher frequency of HLA-B*40, HLA-B*45, HLA-B*53 and HLA-C*04 compared with controls, although P was not significant after Bonferroni correction. Regarding HLA class II, only HLA-DRB1*07 revealed statistical significance; nevertheless, it featured more prominently in controls than patients (P=0.04; Pc=0.52; OR=0.29; 95%; CI=0.07 to 1.25). P was not significant after Bonferroni correction. Conclusions: The development of AA does not seem to be associated with HLA in white Brazilians, nor with susceptibility or resistance. The studies were carried out in populations with little or no miscegenation, unlike the Brazilian population in general, which could explain the inconsistency found.
Assuntos
Humanos , Masculino , Feminino , Adolescente , Adulto , Pessoa de Meia-Idade , Adulto Jovem , Antígenos de Histocompatibilidade Classe I/genética , Antígenos de Histocompatibilidade Classe II/genética , Brasil , Antígenos de Histocompatibilidade Classe I/sangue , Antígenos HLA-B/genética , Antígenos HLA-B/sangue , Antígenos HLA-C/genética , Antígenos HLA-C/sangue , Antígenos de Histocompatibilidade Classe II/sangue , Estudos de Casos e Controles , Estudos Transversais , População Branca , Alopecia em Áreas/genética , Alopecia em Áreas/imunologia , Cadeias HLA-DRB1/genética , Cadeias HLA-DRB1/sangue , Frequência do Gene/genéticaRESUMO
OBJECTIVE: The aim of the present study was to determine the genotype association for alleles of class II human leukocyte antigens (HLA) in the DRB1* locus among blood donors at the Fundação Hemope (Brazil) infected by or immunized for the hepatitis B virus (HBV). METHODS: A case-control study was performed, comprising a group of individuals infected by HBV and a control group of immunized individuals at a proportion of 1:4. Blood samples were taken for the HLA typing of the DRB1* locus. Univariate and multivariate analyses were performed for the assessment of associations between the categorical variables using the chi-squared test and Fisher's exact test. RESULTS: A total of 320 blood donors were analyzed (241 males [75%] and 79 females [25%] with a mean age of 39 years). The case group consisted of 64 HBV-infected donors and the control group was composed of 256 HBV-immunized donors. The multivariate analysis stratified by gender revealed that the DRB1*09 allele was associated with infected male donors (p = 0.016) and the DRB1*08 allele was associated with infected donors aged 39 years or younger (p = 0.031). CONCLUSION: The results of the present study reveal that younger blood donors and male blood donors who respectively exhibit the DRB1*08 and DRB1*09 alleles are more susceptible to intensification of HBV infection.
OBJETIVO: O objetivo do presente estudo foi determinar a associação genotípica dos alelos de classe II dos antígenos leucocitários humanos (HLA) presentes no locus DRB1* entre doadores de sangue da Fundação Hemope (Brasil), infectados pelo ou imunizados contra o vírus da hepatite B (HBV). MÉTODOS: Estudo caso-controle foi realizado com um grupo de indivíduos infectados pelo HBV e um grupo controle composto de indivíduos imunizados na proporção de 1:4. Amostras de sangue foram coletadas para a tipagem HLA do locus DRB1*. Análises univariada e multivariada foram realizadas para a avaliação de associações entre as variáveis categóricas pelo teste do qui-quadrado e teste exato de Fisher. RESULTADOS: Um total de 320 doadores de sangue foram analisados (241 homens [75%] e 79 do sexo feminino [25%], com idade média de 39 anos). O grupo de casos consistiu de 64 doadores infectados pelo HBV e o grupo controle foi composto de 256 doadores imunes ao HBV. A análise multivariada estratificada por sexo revelou que o alelo DRB1*09 foi associado com os doadores infectados do sexo masculino (p = 0,016) e do alelo DRB1*08 foi associado com os doadores infectados com idade entre 39 anos ou mais jovens (p = 0,031). CONCLUSÃO: Os resultados do presente estudo revelam que doadores de sangue mais jovens e doadores de sangue do sexo masculino que exibem, respectivamente, os alelos DRB1*08 e DRB1*09, são mais suscetíveis à cronificação da infecção pelo HBV.