Recently, Hb RNA and protein expression have been measured within dopaminergic neurons in mouse, rat, and human brain.5–10 Our group has observed changes in mitochondrial Hb in PD and also in ageing mice.8 Adult human Hb is a heterotetrameric protein composed of two α- and two β-subunits. The gene discussed is GSTM1; the disease is Parkinson disease.