The following DataNodes have no identifier: 1
http://classic.wikipathways.org/instance/WP4536_r110928 http://rdf.wikipathways.org/Pathway/WP4536_r110928/DataNode/c6794 (BGD2)
More details at https://www.wikipathways.org/WikiPathwaysCurator/DataNodesTests/dataNodesWithoutIdentifier