Allele and haplotype frequencies at human leukocyte antigen class I and II genes in Venezuela's population.

Population studies represent an integral part and link in understanding the complex chain of host-pathogen interactions, disease pathogenesis, and MHC gene polymorphisms. Genes of Mongoloid, Caucasoid, and Negroid populations have created a distinctive HLA genetic profile in the Venezuelan population. Our objective was to determine the predominant HLA class I and II alleles and haplotype frequencies in the hybrid population of Venezuela. The study population consisted of 486 healthy unrelated native Venezuelans and 180 families. We examined the frequency of HLA A-B-C, HLA-DQ and HLA-DR genes by polymerase chain reaction and subsequent hybridization with sequence-specific oligonucleotide probes. Phenotypic, allelic and haplotype frequencies were estimated by direct counting and using the maximum-likelihood method. The predominant HLA class I alleles were A*02, A*24, A*68, B*35, B*44, B*51, B*07, B*15 and Cw*07. Regarding HLA class II, the most frequent alleles were DQB1*03 and DRB1*04, DRB1*15, DRB1*13, DRB1*07. The prevailing haplotype was HLA-A*02B*35 DQB1*03 DRB1*04. Some of these alleles and haplotype frequencies were predominantly present in Amerindians (A*02, A*24, B*35, Cw*07, DRB1*04, A*24 B*35). Previous reports have shown high incidence of A*02, B*44, B*51, DRB1*15, DRB1*13, DRB1*07 alleles in several European populations and A*68, B*07, B*15 alleles in African Americans, which could have contributed to the ethnic admixture of the Venezuelan population. We conclude that our results provide strong evidence that Venezuela's population represents an admixture of the primitive Mongoloid Aborigines, Caucasoid Europeans and Western African Negroid migrants.

Genotype F prevails in Venezuelan urban patients with chronic hepatitis B.

Hepatitis B virus (HBV) has been classified into 8 genotypes (A-H). Genotypes A, D and F have been identified in some South American countries, but in Venezuela studies have been more restricted to aboriginal communities where genotype F is predominant. The aim of the present study was to identify the prevalence of HBV genotypes among native HBsAg carriers in Venezuelan urban areas. In addition, we correlated the predominant HBV genotype with epidemiological, serological and virological features of the infection. Non-Venezuelan migrant patients were excluded from this study. Serum samples from 90 patients (21 children and 69 adults) with chronic hepatitis B (CHB) were analyzed. Seventy-four patients had CHB e-antigen positive and 16 CHB e-antigen negative. HBV DNA serum levels of the whole group ranged from 4.1 to 8.8 log10 IU/mL. Patients with CHB e-antigen positive showed significantly higher viral loads (P = 0.0001) than the group with CHB e-antigen negative. Eighty-eight patients (97.8%) exhibited HBV genotype F while two non-related patients (2.2%) were infected with A + F genotypes. Genotype F is the main circulating HBV strain among HBsAg carriers from Venezuelan urban areas. This genotype is associated mostly with CHB eantigen positive and high rate of transmission. Progression to cirrhosis and hepatocellular carcinoma could be major clinical events of this patient population independently of age at acquisition or transmission route.