The following DataNodes have no identifier: 1
http://classic.wikipathways.org/instance/WP3249_r115748 http://rdf.wikipathways.org/Pathway/WP3249_r115748/DataNode/c4bec (HDACs)
More details at https://www.wikipathways.org/WikiPathwaysCurator/DataNodesTests/dataNodesWithoutIdentifier