Evaluation of the safety of foods derived from genetically modified organisms.

Marketing Authorization for foods composed of or derived from genetically modified organisms (GMO) is accompanied by preliminary evaluation of their safety. In view, in particular, of the lack of relevance of classical toxicological tests, this evaluation is based on the concept of <<substantial equivalence>> according to which the novel food is considered to be as safe as the traditional reference food with which the substantial equivalence has been established. However, specific evaluation of the potential risk, especially allergenicity, related to expression proteins of the genes of interest and/or markers remains essential. If the organism used for the transgene is a recognized allergen, the transgenic plant may express an allergenic protein, but sensitive patients should be able to be recruited and used for in vivo and in vitro tests. If the transgene is derived From an unusual dietary allergen or an organism which has never been suspected to be allergenic, sensitive patients cannot be recruited. In this case, evaluation or prediction of allergenicity is based on indirect methods, concerning the physicochemical properties of the foreign protein expressed: stability to heat, acid pH, technological treatments, or resistance to attack by digestive enzymes. A complementary approach is based on analysis of possible sequence homologies between this protein and allergens with a known structure and listed in data banks accessible by Internet. The allergenicity of a food is also usually multigenic which raises the risk of pleiotropic effects on the phenotype of the transformant and, in particular, modification of the level of expression of endogenous allergenic proteins, normally present in conventional cell lines. At the present time, there is no evidence to suggest that GMO are either more or less allergenic than the corresponding traditional organisms. However, their allergenicity cannot be objectively and reliably evaluated in every case. The impact of modern technology on the possible appearance of new allergens must therefore be studied.