The following genes with an identifier have been found but that do not have a mapping to Ensembl: 4
http://classic.wikipathways.org/instance/WP276_r106973 Htr2b with datasource Entrez Gene
http://classic.wikipathways.org/instance/WP276_r106973 Htr1b with datasource Entrez Gene
http://classic.wikipathways.org/instance/WP276_r106973 Adrb2 with datasource Entrez Gene
http://classic.wikipathways.org/instance/WP276_r106973 Drd2 with datasource Entrez Gene
More details at https://www.wikipathways.org/WikiPathwaysCurator/GeneTests/genesWithoutEnsemblMapping