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Further drafting of the guidance on risk assessment and risk management of LMOs with stacked genes or traits

This Discussion Group is now closed. Please see the Calendar of events for upcoming activities.


The objective of this Discussion Group is to provide input for further improvement of the draft guidance document prepared by the AHTEG Sub-working Group on this topic. An advance draft of the guidance material as well as guiding questions are available below.
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    Remarks to the draft outline „stacked events“
    LMO with Stacked Genes
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Guiding questions

The following questions were prepared by the Chair of the SWG to assist the discussions on this topic. Comments on the draft guidance document may be given on the whole draft (e.g. its structure, completeness, etc.) and/or on the different sections.

General remarks
  • Is the structure of the draft clear?
  • Is it complete or are there some aspects missing?

  • Do you have comments on the introduction, would you address additional points?
Scope and definitions
  • Do you have comments on the scope? Is it too narrow? Should all LMOs with stacked genes be covered regardless of the way they were produced?
Points to consider

Point to consider 1 - Assessment of the intactness of the inserted loci and genotypic stability
  • Do you think that some additional molecular characterisation is needed after gene stacking?
  • Do you have comments on the rationale?
  • Is there anything missing?
  • Do you have other comments?
Point to consider 2 - Assessment of potential interactions between combined events and the resulting phenotypic effects
  • Do you have comments on the rationale?
  • Is there anything missing?
  • Do you have other comments?
Point to consider 3 - Assessment of additive, cumulative, synergistic or antagonistic adverse effects of stacked transgenic traits on the conservation and sustainable use of biological diversity in the likely potential receiving environment, taking also into account potential adverse effects to human health
  • Do you have comments on the rationale?
  • Is there anything missing?
  • Do you have other comments?
  • Are the definitions given correct and complete?
  • Do you have any comment or remark on the Appendix?

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Overview of the topic

At its meeting in Montreal end of April 2009 the AHTEG was tasked with taking into consideration the need for further guidance on specific aspects of risk assessment (see report). The ranking done resulted in three additional sub-working groups: (i) on living modified crops tolerant or resistant to abiotic stress; (ii) living modified mosquitoes; and (iii) LMOs with stacked genes or traits. These subworking groups shall produce an outline of a guidance document with a structure as follows (i) points to consider; (ii) rationales for the points to consider; and (iii) relevant bibliographies and supporting documents.

The subworking group on “Stacked Genes” started its work with a series of comments and submissions how to design an outline structured as decided and on the contents of the outline. In addition the members provided relevant publications. Based on these submissions the chair crafted a first draft outline. This first draft was submitted to the members of the group for a first round of comments.

With the comments on the first draft taken into account a second draft was compiled and is presented now to the discussion forum for further consideration and comment.

Main points considered by the SWG:

  • Growing number of LMOs with multiple or stacked transgenes/traits
  • The term "stacking" can refer to processes or situations where multiple, but not necessarily different transgenes are present in one plant genome as a result of conventional crossing of first-level transformation events or as a result of direct transformation.
  • Transformation with a multigene cassette, retransformation with a second construct or simultaneous transformation with different transgene cassettes (cotransformation) are considered as new events and should be dealt with according the road map
  • Some aspects addressed in this outline may be also relevant to these transgene events with multiple transgenes or traits
  • Aim of this doc: to complement the road map on RA and RM and address special aspects of LMOs with stacked transgenes/traits resulting from conventional crossing of first-level transformation events
  • Restriction to plants

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