The role of socioeconomic status in the susceptibility to develop systemic lupus erythematosus in Mexican patients.

INTRODUCTION: Systemic lupus erythematosus (SLE) is an autoimmune inflammatory disorder for which Major Histocompatibility Complex (MHC) genes are well-identified as risk factors. SLE patients have different phenotypes or clinical presentations, which vary among Mexicans. This variation could be explained by ethnicity and admixture. Since socioeconomic status probably limits and change the patterns of migration, this factor could favor inbreeding and homogamy in some geographic areas. Consequently, it could alter or restrict the possibilities of admixture too. Therefore, the socioeconomic status may also have implications in the susceptibility and the clinical heterogeneity of SLE in Mexican patients. METHODS: One hundred twenty-three SLE patients and 234 healthy individuals with Mexican admixed ancestry were recruited. HLA alleles were analyzed using the HLA typing method based on Sequence-based typing (SBT). RESULTS: As expected, it was found an increased frequency of the HLA-DRB1*03:01 allele in all socioeconomic groups when compared with healthy individuals. The susceptibility allele found in the low-income SLE patients was HLA-DRB1*04:05 whereas, the susceptibility alleles for the high-income SLE patients were HLA-DRB1*07:01 (pC = 0.03, OR = 2.0) and HLA-DRB1*11:04 (pC = 0.0004, OR = 5.1). Additionally, the frequencies of two protective alleles HLA-DRB1*14:06 (pC = 0.01, OR = 0.28) and HLA-DRB1*16:02 (pC = 0.04, OR = 0.22) were found diminished. These findings correlate with the admixture differences between low-income and high-income SLE patients. The clinical manifestations showed a different distribution between both groups. Arthritis and neurological disorder were prevalent in low-income SLE patients, while the hematological disorder was prevalent in high-income SLE patients. CONCLUSIONS: These findings suggest that HLA class II DRB1 genes contribute to the susceptibility and protection to develop SLE differently depending on socioeconomic status. Due to this, the clinical manifestations vary among patients and it could be related to different admixture charge.Key Point• HLA class II DRB1 genes contribute to the susceptibility and protection to develop SLE differently depending on socioeconomic status.

PDCD1 gene polymorphisms in different Mexican ethnic groups and their role in the susceptibility to hypersensitivity pneumonitis.

OBJECTIVE: Hypersensitivity pneumonitis (HP) is an immunological disorder caused by antigen exposure in susceptible individuals. The PDCD1 polymorphisms, PD1.3 and PD1.5 have been associated with the susceptibility to inflammatory disorders. This study was conducted to test whether the PD1.3 and PD1.5 polymorphisms are associated with HP in Mexican patients and to explore the distribution of these polymorphisms in different Mexican ethnic groups. DESIGN AND METHODS: We studied 98 Mexican patients with HP and 92 healthy Mexican controls. Also, 156 healthy Amerindian individuals from two ethnic groups were included (96 Mayans and 60 Mayos). Polymorphisms were determined by TaqMan 5' nuclease assays. RESULTS: Significant differences in the distribution of the PD1.3 and PD1.5 genotypes between HP patients and healthy Mestizo controls were not found. We observed a significantly different distribution of these polymorphisms in Mexican Mestizos when compared to the Amerindians. CONCLUSIONS: We found no association between PD1 polymorphism and HP; however the distribution of these polymorphisms was different in Mexican Mestizos and Amerindians.