Eosinophilic esophagitis linked to master gene
Eosinophilic esophagitis (EoE) is the inflammation and accumulation of eosinophils, a specific type of immune cell, in the esophagus. However, it is not an allergy. Symptoms of EoE vary with age: In young children a major symptom is spitting up food, while in older children and adults, the condition may cause food to become stuck in the esophagus.
The symptoms may improve on a liquid formula diet that contains no protein allergens or on a diet that lacks the six major food allergens (milk, soy, eggs, wheat, peanut and seafood).
Little is known about what causes EoE, but the fact that the disease runs in families suggests that specific genes may be involved.
Investigators at Cincinnati Children's Medical Center Hospital performed a genome-wide association analysis in children with EoE and healthy children. This type of study detects markers of genetic variation across the entire human genome and allows researchers to zero in on a region of a chromosome to identify genes that influence health and the development of disease.
In this study, the investigators identified changes in genes within a region on chromosome 5 that were highly associated with EoE. One of the genes in this region encodes a protein called thymic stromal lymphopoietin (TSLP). When the investigators measured the expression levels of this gene in children with EoE, they found it was more highly expressed than in children without the disorder. This result suggests that TSLP plays some role in EoE.
TSLP is made by epithelial cells, which line internal and external surfaces of the body. It has already been described as a master switch that may turn on other allergic diseases, such as asthma and atopic dermatitis (eczema).
Future research is needed to determine if these findings might lead to a genetic test for TSLP and whether drugs that block the production or function of TSLP might be useful in treating EoE.
Rothenberg et al. Common variants at 5q22 associate with pediatric eosinophilic esophagitis. Nature Genetics, 2010; DOI: 10.1038/ng.547
Courtesy of Science Daily
First published in March 2010