Sequences that may pose difficulties in the artificial synthesis of genes include the following:

1. High GC Content: Gene sequences with high GC content may increase the difficulty of artificial synthesis, as GC base pairs have higher stability under laboratory conditions, potentially leading to synthesis challenges and increased costs.

2. Repetitive Sequences: The presence of repetitive sequences may lead to errors during the synthesis process, as complex structures can cause insertions or deletions. These repetitive regions may require additional processing and validation, adding to the complexity of synthesis.

3. Abundance of Restriction Sites: If the target gene contains numerous restriction sites, this may pose challenges to gene synthesis and subsequent gene expression. Such sequences may need modification to avoid cleavage in the host cells.

4. Complex Structural Features:   RNA sequences with complex secondary structures or DNA sequences with specific structural domains may require more sophisticated synthesis strategies to ensure the maintenance of their integrity during the synthesis process.

5. Non-natural Codon Sequences: Introducing non-natural codon sequences or sequences with significant differences in codon usage preferences from the host organism may increase the complexity of synthesis, affecting the efficiency of gene expression.

In summary, these sequence features may complicate gene synthesis, requiring additional optimization and validation steps to ensure the successful generation of functional artificially synthesized genes.

GenCefe’s professional team has extensive experience in synthesizing difficult genes. View  our case   studies   of  difficult gene synthesi s: https://www.gencefebio.com/GeneSynthesis/93.html