Welding and Parkinson disease

The cause of Parkinson disease (PD) remains unknown. Progress has been made on the genetic front with the identification of specific gene mutations (e.g., α-synuclein) associated with familial Parkinson syndromes. Because of their clinical heterogeneity there remains debate as to whether these genetic syndromes are representative of what has been considered classical PD. The identification of mutations in the parkin and LRRK2 genes in both familial and sporadic PD1,2 suggest that genetic mutations may be more common than previously estimated. Despite these advances, at least 80% of PD cases do not have a clear genetic or familial basis. The knowledge that different genetic mutations can produce the PD phenotype suggests that perhaps there is no single clinical entity PD, but rather that PD is an amalgamation of many different conditions that simply have a greater or lesser degree of phenotypic overlap. However, most clinicians and scientists still endorse the classical concept of idiopathic PD. See also pages 2021 and 2033 For the condition generally referred to as idiopathic PD and characterized by asymmetric onset of rest tremor, bradykinesia and rigidity, responsiveness to dopaminergic treatment, and the classic pathology of nigral degeneration with Lewy bodies, the cause remains unknown. Because genetic causes appear identifiable in only a minority of cases, there has been an extensive search for potential environmental causes. This search has been fueled by the identification of individuals who developed parkinsonism following exposure to MPTP through injection drug use and epidemiologic links between PD and environmental exposure to agricultural chemicals. Another environmental topic of recent interest has been the potential relationship between occupational welding fume exposure and PD. Welding fume is the cloud of smoke that is produced when welding metals. This fume, like cigarette smoke, is a combination of many different chemicals in a complex interaction. The …