Interestingly, the robust decrease in stride length found in the Tph1 (−/−) is similar to that in a recently published C57BL/6J mouse model of Parkinson's disease using 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine to induce lesions of the substantia nigra [28]. The gene discussed is TPH1; the disease is Parkinson disease.