GSTM1 and Parkinson disease: However, it has been reported that when dopaminergic neurons were challenged with α-syn, Hb-α-syn complex formation was initiated in the mitochondria and cytoplasm, together with reduced transport of Hb from cytoplasm to the mitochondria, low levels of free mitochondrial Hb, and Hb aggregation in the nucleus, contributing to neuronal cell damage and pathological progression of PD.