How should sequence variants be represented in a sequence listing?

This page is an FAQ based on guidance from the Manual of Patent Examining Procedure. It is provided as guidance, with links to the ground truth sources. This is information only: it is not legal advice.

Sequence variants should be represented as follows:

1. Each variant that meets the length threshold must be included in the sequence listing with its own sequence identifier.
2. Variants disclosed as a single sequence with enumerated alternative residues should be represented using the most restrictive ambiguity symbol.
3. Variants disclosed only by reference to deletions, insertions, or substitutions in a primary sequence should be included in the sequence listing.
4. Use appropriate feature keys and qualifiers to describe variants:

• For nucleic acids: use “variation” or “misc_difference” feature keys
• For amino acids: use “VAR_SEQ” or “VARIANT” feature keys

The MPEP states: “A primary sequence and any variant of that sequence, each disclosed by enumeration of its residues and specifically defined to meet the definition in 37 CFR 1.831(a) and 1.831(b), must each be included in the “Sequence Listing XML” and assigned its own sequence identifier.“