[Parkinson's disease: Role of genetic and environment factors. Involvement in everyday clinical practice].

Genetics and exposure to toxins constitute the main determinants in the onset of Parkinson's disease (PD). At least, 13 loci and nine genes involved in familial and sporadic forms have been described. A significant association between occupational exposure to pesticides (especially insecticides) and PD has been confirmed recently with rare cases even being recognized as occupational disease. We develop in this paper a practical approach for such situations where a common genetic or toxic origin is suggested. Such an approach can be applied very broadly using case by case study then further analysis in a specialized center of reference in the field of genetics or occupational diseases and the environment. A pedigree needs to be drawn to evaluate a potential genetic factor with, if possible, the examination of various family members. Depending on the mode of inheritance, age of disease onset and phenotypic expression, genetic analysis will be carried out (mainly the study of parkin gene for recessive transmission and LRRK2 gene for dominant transmission). The evaluation of a toxic factor is more difficult because its direct involvement may not always be defined with certainty, the collection of information is more complex (product list, causal relationship, protection system used...). The course of action will identify the existence of a potential risk factor particularly in patients at risk (farmers, workers in a factory using heavy metals) by considering secondary specialized consultation with the occupational physician or pathology consultation work for possible development of a procedure for recognition of occupational disease.