HPGDS and Parkinson disease: In fact, a previous study showed that loss of GstS1 function enhanced the loss of dopaminergic neurons in a parkin mutant, a Drosophila model of Parkinson’s disease and conversely, overexpression of GstS1 in the same dopaminergic neurons suppressed dopaminergic neurodegeneration in such mutants (Whitworth et al. 2005).