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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 should I do if the IDT online ordering tool says that my sequence is too complex to order, but I need it as is?

In most cases, our system has found a region with either very high G/C content or several small repeats that would prevent us from synthesizing your sequence.

If your sequence contains a coding region, you can use codon optimization to reduce the complexity. Codon optimization uses synonymous codons to retain the final amino acid sequence that is expressed while generating a sequence that we can synthesize.

If your sequence is not a coding region, we might be able to synthesize the sequence as a custom gene, which is delivered in a basic pUC vector, rather than just a linear, dsDNA gBlocks fragment. For assistance, send your sequences and any questions to


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