We previously used this technique to examine the 2D relationship between TH (as a proxy for dopamine) and Fe levels in a mouse model of Parkinson's disease: the autooxidation of dopamine is a potent source of reactive oxygen species in Parkinson's disease and is promoted in the presence of Fe,40 but prior to our study, little was known about the regional distributions of Fe in the parkinsonian brain. The gene discussed is TH; the disease is Parkinson disease.