How should regions of contiguous ‘X’ residues be described in an amino acid sequence?

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.

The MPEP 2412.05(d) provides guidance on describing regions of contiguous ‘X’ residues in amino acid sequences:

• Use the syntax “x..y” as the location descriptor
• Apply this for regions with a known number of contiguous ‘X’ residues
• Use this approach when the same description applies to all ‘X’ residues in the region

The MPEP states, “WIPO Standard ST.26, paragraph 34, provides that a region containing a known number of contiguous “X” residues for which the same description applies may be jointly described using the syntax “x..y” as the location descriptor in the element INSDFeature_location” (see MPEP § 2413.01(g) subsection IV, for information regarding INSDFeature_location). This approach simplifies the representation of regions with multiple unknown amino acids in sequence listings.