title: HLA class II and class I polymorphism in Venezuelan patients with myasthenia gravis.
abstract: Oligotyping performed among ethnically mixed Venezuelan patients with myasthenia gravis (MG) and controls has revealed positive associations of HLA class I A*31, B*08, B*39, B*40, C*15, C*17, and class II DRB1*09 and negative associations of DQB1*06 and DQA1*02 with the disease. Sequential removal of human leukocyte antigen B (HLA-B) alleles when relative predispositional effects (RPEs) were looked for demonstrated that B*08 is the allele group with the largest contribution in the overall MG patients followed by B*39 and B*40. Several specificities (A*31, B*08, C*17, DRB1*03, DQA1*05, and DQB1*02) indicated increased frequencies among patients with thymic hyperplasia versus patients without hyperplasia or controls. Tests to identify alleles with the strongest association to MG in our patients detected DRB1*13 and B*38 as possible predisposing secondarily associated alleles in patients with hyperplasia. The associations observed disappear after Bonferoni correction of probability values and have been described in patients of Caucasian and/or Oriental ethnic background. Thus, our results reflect the heterogeneity of our population and of the patients tested and suggest a limited influence of several HLA genes in this heterogeneous disease or that these might be only markers of nearby non-HLA genes responsible for the susceptibility or resistance effect.
authors.affiliation: Centro de Medicina Experimental Miguel Layrisse, Instituto Venezolano de Investigaciones Científicas, Caracas, Venezuela.
authors.forename: Mercedes T
authors.initials: MT
authors.lastname: Fernández-Mestre
authors.forename: Vivian
authors.initials: V
authors.lastname: Vargas
authors.forename: Silvia
authors.initials: S
authors.lastname: Montagnani
authors.forename: Maritza
authors.initials: M
authors.lastname: Cotúa
authors.forename: Violeta
authors.initials: V
authors.lastname: Ogando
authors.forename: Zulay
authors.initials: Z
authors.lastname: Layrisse
mesh_terms: D000328:Adult; D000483:Alleles; D001327:Autoimmune Diseases / Q000453:epidemiology / Q000235:genetics*; D005006:Ethnicity / Q000235:genetics; D005260:Female; D005787:Gene Frequency; D005805:Genes, MHC Class I; D005802:Genes, MHC Class II; D020022:Genetic Predisposition to Disease; D006801:Humans; D006965:Hyperplasia; D008297:Male; D008875:Middle Aged; D009157:Myasthenia Gravis / Q000453:epidemiology / Q000235:genetics* / Q000473:pathology; D010641:Phenotype; D011110:Polymorphism, Genetic; D013945:Thymoma / Q000150:complications / Q000453:epidemiology / Q000235:genetics; D013950:Thymus Gland / Q000473:pathology; D013953:Thymus Neoplasms / Q000150:complications / Q000453:epidemiology / Q000235:genetics; D014687:Venezuela / Q000453:epidemiology