What Is an FNA File?

This article explains what an FNA file is, how to open one, and how to save one to a different format like FASTA, GB, VCF, images, etc.

What Is an FNA File?

A file with the FNA file extension is a FASTA format DNA and protein sequence alignment file that stores DNA information that can be used by molecular biology software.

FNA files, specifically, may be used to hold just nucleic acid information while other FASTA formats contain other DNA-related information, such as those with the FASTA, FAS, FA, FFN, FAA, FRN, MPFA, SEQ, NET, or AA file extension.

These text-based FASTA formats originally arose out of a software package with the same name, but are now used as a standard in DNA and protein sequence alignment applications.

How to Open an FNA File

Open one in Windows, macOS, and Linux with Geneious (it's free for a limited time, usually 30 days). To do this, navigate to the File > Import menu and choose to import the file via the From File menu item.

You might also be able to open one with BLAST Ring Image Generator (BRIG).

Try Notepad++ or another text editor if those ideas aren't working out. The file might indeed be text-based and simple to read, or you might find that it has nothing to do with the FASTA format, in which case opening the file as a text document may reveal text that identifies what was used to create the file or what format the file is in.

How to Convert an FNA File

I can't verify this because I don't have an FNA file to try it out, but you should be able to use Geneious to convert the file to lots of other formats, like FASTA, GB, GENEIOUS, MEG, ACE, CSV, NEX, PHY, SAM, TSV, and VCF. This can be done through the program's File > Export menu.

That same program should also be able to save the file to PNG, JPG, EPS, or PDF, via File > Save As Image File.

Although you can't normally just rename a file's extension to something else and expect it to work in the same manner, you can rename a .FNA file to a .FA file if your particular DNA sequencing software will only recognize the FA format.

Still Can't Open It?

If after using the programs from above, you still can't get your file to open, you might find that the file extension doesn't actually read .FNA but instead something that just looks similar.

For example, FNG (Font Navigator Group) files look an awful lot like they say ".FNA" but if you look closely, only the first two letters are the same. Since the file extensions are different, it's an indication that they're of a different file format and will most likely not work with the same programs.

The same could be said for many other file extensions like FAX, FAS (Compiled Fast-Load AutoLISP), FAT, FNTA (Aleph One Font), FNC (Vue Functions), and FND (Windows Saved Search).

The idea here is to just make sure the file extension reads .FNA. If it does, try again to use the programs from above to open or convert it. If you have a different kind of file, research its extension to find out which applications are needed to open or convert it.