Genetic variations in the TLR3 locus are associated with eosinophilic esophagitis

Background Eosinophilic esophagitis (EoE) is an antigen-driven disease mediated by an abnormal immune Th2 response. Objective The objective of this article is to investigate genes associated with regulating immune responses leading to disease susceptibility. Methods Twenty-seven tag single nucleotide polymorphisms (tSNPs) selected in five candidate genes ( TLR3, TLR4, FOXP3, FLG and TSLP) were genotyped in 218 EoE patients and 376 controls. Skin prick tests were carried out in EoE patients with a panel of 17 aeroallergens and 22 plant- and animal-derived foods. Results Five tSNPs located in the TSLP locus and one tSNP located in the TLR3 locus were significantly associated with EoE. The interactions between TLR3 and TSLP loci were analyzed. TLR3+/TSLP– and TLR3–/TSLP+ individuals showed a significantly reduced susceptibility to EoE compared to TLR3–/TSLP– individuals (OR = 0.66, p = 0.036 and OR = 0.23, p = 0.00014, respectively). Likewise, TLR3+/TSLP+ individuals showed the most decreased susceptibility of developing EoE (OR = 0.16, p = 0.0001). However, the interaction gain attributed to the combination of both genes was negative (IG = –4.52%), which indicated redundancy or independent effect. Additionally, TLR3 locus was found to be associated with aeroallergen and food sensitization in EoE patients (OR = 9.67, pc = 0.025 and OR = 0.53, pc = 0.048, respectively). Conclusion TLR3 constitutes a novel genetic susceptibility locus for developing EoE, and the effects would be independent of TSLP.

Renin–angiotensin–aldosterone system genotypes and haplotypes affect the susceptibility to nephropathy in type 2 diabetes patients

Background: The association between renin C-4063T and angiotensinogen (AGT) T174M, M235T, and A-6G polymorphisms with diabetic nephropathy (DN) was investigated in Tunisian type 2 diabetes (T2DM) patients. Methods: Study subjects comprised 917 T2DM patients (405 normoalbuminuric, 329 microalbuminuric and 185 macroalbuminuric). Genotyping was done by PCR-RFLP. Results: Renin C-4063T allele and genotype frequencies were comparable between DN cases and normoalbuminuric controls. Although AGT 235T and -6G allele, and 235T/T and -6G/G genotype frequencies were higher in DN compared to normoalbuminuric patients, they were comparable between microalbuminuric or macroalbuminuric patients. Three-locus AGT haplotype analysis (A-6G/T174M/M235T) identified DN-protective (ATM, AMM, GTM) and DN-susceptible (GTM, ATT, GMT and AMT) haplotypes, and demonstrated enrichment of GTT haplotype in macroalbuminuric compared to microalbuminuric or normoalbuminuric patients. Regression analysis confirmed negative (AMM) and positive (GTM, ATT, GMT, AMT) association of AGT haplotypes with microalbuminuria, and negative (AMM) and positive (GTM and ATT) association of AGT haplotypes with macroalbuminuria. None of the AGT haplotypes was associated with DN severity. Conclusions: Genetic variation at the AGT gene influences the risk of nephropathy in T2DM patients but not extent of DN severity, and thus represents a potential DN genetic susceptibility locus worthy of replication.