The value of SwissOF1-En1+/− mice as a model for PD-like degeneration is strengthened with evidence of DN degeneration predominantly in the SNpc, and to a lesser extent in the VTA, loss of terminal synaptic function of DNs with reduced dopamine in the striatum, changes in autophagic function and presence of enlarged ovoid-like varicosities (here called ‘axonal swellings’) on dopaminergic nigrostriatal axons20, 28. The gene discussed is EN1; the disease is Parkinson disease.