Case-control study and mRNA expression analysis reveal the MyD88 gene is associated with digestive disorders in...

As in humans, significant associations between Toll-like receptor 4 (TLR4) and digestive disorders have been identified in rabbit and dog. However, as an essential adaptor downstream of TLR4, the genetic variation of myeloid differentiating factor 88 (MyD88) and its association with digestive disorders have remained unknown. In this study, we detected 10 single nucleotide polymorphisms (SNPs) in the entire genomic region of rabbit MyD88. The genetic variation in susceptibility to digestive disorders for the only coding SNP (synonymous c.699T>C) was studied in Yaan (183 cases and 142 controls) and Chengdu populations (145 cases and 140 controls). A case-control association study revealed that individuals with the C allele had significant protection against digestive disorders in the Yaan population (OR = 0.71; 95% CI, 0.51-0.99; P < 0.05), the Chengdu population (OR = 0.55; 95% CI, 0.39-0.78; P < 0.01) and for joint analysis (OR = 0.62; 95% CI, 0.49-0.79; P < 0.01). We also experimentally induced digestive disorders by feeding a fiber-deficient diet and found that increased susceptibility was significantly associated with higher MyD88 mRNA expression (P < 0.05). The lowest MyD88 mRNA expression was observed in individuals carrying the protective CC genotype. These results suggest that MyD88 is one of the most plausible candidate genes in relation to digestive disorders in rabbit. Further studies are required to explore the biological implications of MyD88 in the pathogenesis of digestive disorders.