However, Ts65Dn mice contain an extra copy of 60 genes (35 protein coding) located on Mmu17 (orthologous to Hsa6) that are not triplicated in people with Down syndrome and the resultant Ts65Dn phenotypes may be more severe than those seen in the human condition or possess spurious phenotypes not relevant to Down syndrome.3, 60, 61 Other mouse strains have therefore been developed with partial trisomy of genes on Mmu16. The gene discussed is OR4Q3; the disease is Down syndrome.