Wheat is an important staple food, but the gluten in wheat can cause illness or allergy in some people. Gluten is a term used to describe two families of proteins: glutenins and gliadins. People with Celiac Disease (CD) have painful digestive symptoms when they eat gluten. The symptoms are caused by the gliadin, not the glutenin, in wheat flour. Wheat is also a common cause of food allergies. One allergy in particular, Wheat-Dependent Exercise Induced Anaphylaxis (WDEIA) occurs when sensitive individuals ingest gluten, then engage in intense physical exercise. Like CD sufferers, people with WDEIA are reacting to gliadin, not glutenin. In fact, people with WDEIA react to a subset of gliadin proteins called omega-5 gliadins. In an effort to create a wheat flour that WDEIA-sensitive individuals can eat without risk, USDA researchers Susan Altenbach and Paul Allen used genetic engineering to reduce only the omega-5 gliadin proteins in wheat.
Altenbach and Allen attempted to reduce the omega-5 gliadin proteins in wheat grain, those that cause the WDEIA allergy, using a technique called RNAi*. The genetically engineered (GE) wheat grain from plants generated by this technique had reduced omega-5 gliadin protein, as predicted, apparently without affecting other gliadin proteins in the grain. Although not yet tested, the hope is that WDEIA susceptible individuals will be able to eat products made from this wheat without risk of allergic reaction.
As described in a previous post, RNAi was used by other researchers (see Gil-Humanes, et al., 2010) to reduce gliadin proteins in wheat. The GE wheat generated by Gil-Humanes and colleagues has reduced amounts of all gliadins, not just the omega-5 subset that causes WDEIA symptoms. Will flour made from reduced-gliadin GE wheat alleviate symptoms in people who have either CD or WDEIA? By extension, will flour made from GE wheat which is lower only in the omega-5 gliadins reduce WDEIA but not CD? Future research will answer these questions.
*RNA interference (RNAi) is a technique for preventing a gene from making protein. For more information, see this explanation on MedicineNet.
Altenbach, S., & Allen, P. (2011). Transformation of the US bread wheat ‘Butte 86’ and silencing of omega-5 gliadin genes GM Crops, 2 (1), 66-73 DOI: 10.4161/gmcr.2.1.15884
Gil-Humanes, J., Pistón, F., Tollefsen, S., Sollid, L.M., Barro, F. (2010). Effective shutdown in the expression of celiac disease-related wheat gliadin T-cell epitopes by RNA interference. PNAS 107, 17023 – 17028. DOI: 10.1073/pnas.1007773107