The aim of this paper is to contribute to the evaluation of the present state of lexical-discursive development in scientific texts written in Basque. More specifically, it focuses on the study of terminological variation in texts on genetic engineering of different degrees of specialization. It describes the patterns of variation found in those texts, and attempt to relate such patterns to different types of sociolinguistic and discourse factors. The sociolinguistic factors are mostly associated with the incomplete normalization of Basque. For that reason, we also discuss the issue of terminological variation in languages undergoing normalization and we propose a set of recommendations based in this study, which we feel should be borne in mind during the normalization of terminology of those languages.