The following genes with an identifier have been found but that do not have a mapping to Ensembl: 2
http://classic.wikipathways.org/instance/WP785_r117218 LDLR with datasource Entrez Gene
http://classic.wikipathways.org/instance/WP785_r117218 FZD5 with datasource Entrez Gene
More details at https://www.wikipathways.org/WikiPathwaysCurator/GeneTests/genesWithoutEnsemblMapping