GSTM1 and Parkinson disease: Several intriguing observations suggest Hb as a potential player in PD.34 Its distribution in mesencephalic DA neurons enlists Hb into the small number of genes whose expression correlates with cells' vulnerability.2, 12α- and β-Chains mRNAs were found strongly downregulated in DA neurons of rats treated with low doses of rotenone.35 Intriguingly, they were upregulated in post mortem PD brains.36 Furthermore, Hb and α-synuclein complex was recently found in brain tissue and red blood cells of aging cynomolgus monkeys.37