Extract tissue from patient, build a cell line, CRISPR in vitro, build a cell line, sequence to verify. Use verified cell line to build pseudo-organs or to inject cells or stem cells.

ex vivo gene therapy.

Cells don't survive sequencing, any that you do implant have not been sequenced. At best you can get some confidence that the error rate is small.

This is why I said build a cell _line_, i.e. cells that all come from a single parent cell. Clones. Make monoclonal stem cell lines, use CRISPR on them, make a NEW monoclonal cell line post-CRISPR and pull some cells to validate success or failure.