Analysis of Genetic Polymorphism of the HLA-B and HLA-DR Loci in Patients with Dermatophytic Onychomycosis and in Their First-Degree Relatives

Onychomycosis is known to have predisposing factors and a high prevalence within families that cannot be explained by within-family transmission. We determined the frequency of HLA-B and HLA-DR haplotypes in 25 families of Mexican patients with onychomycosis in order to define the role of the class II major histocompatibility complex (MHC) in genetic susceptibility to this infection. Seventy-eight subjects participated in the study, 47 with onychomycosis and 31 healthy individuals. The frequencies of the HLA-B and HLA-DR haplotypes were compared with those found in first-degree relatives without onychomycosis and in a historic control group of healthy individuals. The frequencies in the controls were similar to those of the healthy relatives of the patients. However, on comparison of the patients with historic controls, we detected a higher frequency of the HLA-DR8 haplotype (P=.03; odds ratio, 1.89; 95% confidence interval, 0.98–36). These findings suggest that there are polymorphisms in genes of the MHC that increase susceptibility to onychomycosis, particularly haplotype HLA-DR8.

ResumenEn la onicomicosis hay factores predisponentes conocidos y una alta prevalencia en familiares no explicada por transmisión intrafamiliar. Analizamos la frecuencia génica de alelos de los genes HLA-B y HLA-DR en 25 familias de pacientes mexicanos con onicomicosis para conocer el papel del complejo mayor de histocompatibilidad (MHC) clase II en la susceptibilidad genética a esta enfermedad. Se estudiaron 78 individuos, 47 de ellos con onicomicosis y 31 sanos. Se determinaron las frecuencias génicas de los alelos de los loci HLA-B y HLA-DR y se compararon con las presentes en familiares de primer grado sin onicomicosis y con un grupo de individuos sanos. Estas fueron semejantes a las de familiares sanos; sin embargo, al comparar pacientes con controles históricos se encontró un aumento de la frecuencia del alelo HLA-DR8 (p=0,03; OR=1,89; IC 95%: 0,98–36). Estos datos sugieren que dentro del MHC existen genes de susceptibilidad al desarrollo de onicomicosis; en particular con el alelo HLA-DR8.