# Adding a Cytoband

Click the **+ Add reference files** button under the [*Reference Files* section header](https://help.partek.illumina.com/partek-flow/user-manual/settings/components/library-file-management/adding-library-files-on-the-library-file-management-page) and choose **Cytoband** from the *Library type* drop-down list in the *Add reference sequence* dialog (Figure 1). If a reference sequence is already associated with an assembly, *Cytoband* will be the only option available in the *Add reference sequence* dialog and will not appear in a drop-down list (Figure 1).

![](https://1384254481-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FJVEESmJAPppJ3ijFq5aR%2Fuploads%2Fgit-blob-cb9b75c808eb20607a55fec75945f672f8a2be2b%2Fchoose-lib-cytoband.png?alt=media)

![Figure 1. Add reference sequence dialog. If the reference sequence and cytoband files have not been added yet, both options will appear in the Library type drop-down list (top). If one is missing, it will appear as the only option (bottom). For many model organisms, automatic downloads are available from the Partek repository](https://1384254481-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FJVEESmJAPppJ3ijFq5aR%2Fuploads%2Fgit-blob-98cea3ba27c995304647408ff27ed98148625415%2Fcytoband-only.png?alt=media)

If you are using an assembly supported by Partek (e.g. human), select **Download cytoband** and click **Create** to get the cytoband file from the Partek repository. Alternatively, select **Build cytoband** and select .fasta files or .2bit files to to build the cytoband file. If the reference sequence is missing, it will either be downloaded automatically or you will be asked to import it from another source (see [*Adding a reference sequence*](https://github.com/illumina-swi/partek-docs/blob/main/docs/partek-flow/user-manual/settings/components/library-file-management/adding-a-reference-sequence-md/README.md)).

If you are using a custom assembly (e.g. for a non-model organism), the *Download cytoband* option will not be available (Figure 2).

![Figure 2. For custom assemblies, automatic downloads are not available so the cytoband has to be created](https://1384254481-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FJVEESmJAPppJ3ijFq5aR%2Fuploads%2Fgit-blob-eb4d83bbc0e5b0de2d216e60798627c0d0b4b881%2Fnon-model-cytoband.png?alt=media)

## Additional Assistance

If you need additional assistance, please visit [our support page](http://www.partek.com/support) to submit a help ticket or find phone numbers for regional support.