The discovery of several genes linked to Parkinson disease (PD) in recent years has spawned extensive research efforts to elucidate the underlying mechanism of this prevalent neurological disorder. This issue's Hot Paper focuses on the discovery of a third gene, DJ-1, which is mutated in a small subset of patients with PD.[1] Neurologist and geneticist Vincenzo Bonifati, along with molecular biologists Ben Oostra and Peter Heutink and colleagues at Erasmus University Medical Center in Rotterdam, showed that DJ-1 mutations are implicated in a form of autosomal recessive, early-onset PD. Genetic mapping of regions implicated in parkinsonism among members of two different families revealed a deletion in the DJ-1 gene among members of one family, and a point mutation in members of the other.