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Frequently asked questions

Our Scientific Applications Support team has assembled a list of frequently asked questions to help you find answers quickly. Filter using one or more categories to focus on specific topics, or use the search bar to perform a text search.

How do I choose which two guide RNAs to multiplex, when using the Alt-R® nickases?

There are multiple factors to consider when selecting the guide RNAs to multiplex with Cas9 nickase:

  • Each crRNA should function efficiently in individual genome editing experiments.
  • The two crRNAs must target opposite strands to ensure a double-strand break is created.
  • Distance between cleavage sites is important for optimal performance.
    • Alt-R Cas9 D10A Nickase 3NLS: 40–70 bp
    • Alt-R Cas9 H840A Nickase 3NLS: 50–70 bp
  • Outward PAM site orientation (right side)



For more information about the design and use of Cas9 nickases, refer to the application note at (Support section).