Standards for the publication of mouse mutant studies

Institute of HumanMovement Sciences and Sport, ETH Zurich, Zurich, Switzerland*Corresponding author: W. E. Crusio, Centre de NeurosciencesInte´gratives et Cognitives, Universite´ de Bordeaux, CNRS UMR5228, Bat B2 - Avenue des Faculte´s, 33405 Talence, France.E-mail: wim_crusio@yahoo.comSince Genes, Brain and Behavior (G2B) started publication in2002, the journal has become one of the favored outlets for,among many other subjects, mouse mutant studies. Unfor-tunately, a significant proportion of mutant studies sufferfrom serious methodological problems, which are the mostfrequent reason of rejection without review for manuscriptssubmitted forpublication to G2B. Most of theseproblems arecurrently not always appreciated in the field and authorssometimesprotestsuchsummaryrejectdecisionsbyarguingthat they followed commonly used procedures that manyother journals publish without any problem. Of course, therealissueiswhetherornotthesecommonlyusedproceduresare scientifically valid. The problems vary from improperbreeding procedures to invalid choices of control animals.Examples of such studies can be found in virtually everyscientific journal, even the most prestigious ones. Because ofthepaucity ofmethodological informationthatmanyso-calledhigh-impact journals provide nowadays, it is often evenimpossible to verify what genetic background was employedand whether proper procedures were followed and one justhas to hope for the best. Many of these problems werepointed out by Gerlai (1996) and it is very disappointing andrather distressing, to say the least, to see that more thanadecadeafterGerlai’soriginalcommentaryappeared,articlescontinue to be published that violate some of the most basicrequirements for the proper conduct of mutant studies.Clearly this situation is highly unsatisfactory and the currentsituation is not only frustrating to authors, reviewers andeditors alike, but to the extent that these design faults areobvious fatal flaws, this also constitutes a waste of time,effort and research resources, not to mention the ethicalimplications of unnecessarily using live animals for flawedstudies. The following editorial will therefore outline theminimum standards a mutant study needs to comply within order to be considered for publication in G2B (Table 1). Manuscripts that do not adhere to these minimum require-ments will be rejected for publication without review,whereas manuscripts that do not provide sufficient experi-mental detail will be returned to their authors for completionbefore being sent out for review. It is hoped that otherjournals publishing mutant work will follow our lead, resultingin a critical improvement of the designs of mutant studies. (Sometimes authors refer to an earlier publication for ‘moredetails’. Although this may be acceptable to avoid repeatingmore arcane details of some experimental procedure, anymanuscript should always contain all experimental detailsnecessary for reviewers (and readers! ) to understand whathad been done. )In what follows we will briefly discuss the most commonproblems with the design of mutant studies and brieflyexplain why they are not acceptable. For more detailed dis-cussions and acceptable alternative approaches, the reader isreferred to Crusio (2004), Gerlai (1996, 2000, 2001) andWolfer et al. (2002). It should be noted that basically all ofthe problems discussed are common to any mutant study,regardlessofwhetherthemutation wasinducedinatargetedway by means of transgenesis or homologous recombination(‘knock-out’), or was induced randomly following chemicaltreatmentorradiation,oroccurredspontaneously.Inaddition,most of the recommendations given obviously also apply toother species than rodents.