Luxembourg notified to the European Commission its scientific arguments justifying the implementation of a national safeguard measure prohibiting the placing on the market of GM potato EH92-527-1 for cultivation purposes in Luxembourg, after which the European Commission asked the European Food Safety Authority (EFSA) to assess the scientific information supporting the prohibition. Having considered the information package provided by Luxembourg and all relevant scientific publications, the EFSA Panel on Genetically Modified Organisms (GMO Panel) concluded that: (i) no new data specific to the safety of the npt II gene have been provided; (ii) although bacterial DNA release and development of competence are expected to occur more efficiently in biofilms, the link between resistance in biofilms and cultivation/processing of GM potato EH92-527-1 was not established by Luxembourg, and the main barriers, limiting the transformation frequency of bacterial cells with transgenic plant DNA, remain; (iii) the risk posed by the formation of mosaic structures of aminoglycoside phosphotransferase genes could not be assessed without data documenting the existence of such structures among the existing gene variants, and such data were not provided; (iv) the knowledge gaps and uncertainties highlighted in the Luxembourgeois document and the therapeutic relevance of kanamycin and neomycin have already been considered in the previous EFSA opinion on antibiotic resistance marker genes, and no new information on the safety of npt II gene as present in the GM potato EH92-527-1 has been identified in the scientific literature that would cause the GMO Panel to change its previous conclusions. Therefore, the EFSA GMO Panel concludes that no grounds exist to date that would lead to reconsideration of its opinion on GM potato EH92-527-1.