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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.

What is the recommended length for the CRISPR-Cpf1 crRNA guide?

For the Alt-R® CRISPR-Cpf1 crRNA, the input sequence can vary between 20 and 24 nucleotides. However, based on internal studies, we recommend using a 21-nucleotide sequence as input into the CRISPR-Cpf1 crRNA ordering tool (accessible at

The ordering tool will automatically convert the DNA sequence to RNA during the ordering process. The 20-base constant region (loop domain) and modifications that confer intracellular nuclease resistance will be automatically added. The final Alt-R CRISPR-Cpf1 crRNA will be 40–44 bases.