The following genes with an identifier have been found but that do not have a mapping to Ensembl: 2
http://classic.wikipathways.org/instance/WP702_r137565 CYP450 with datasource Pfam
http://classic.wikipathways.org/instance/WP702_r137565 Glutathione transferase with datasource Pfam
More details at https://www.wikipathways.org/WikiPathwaysCurator/GeneTests/genesWithoutEnsemblMapping