[Parkinson disease: monogenic forms and genetic susceptibility factors]

Parkinson's disease (PD) is one of the most frequent neurodegenerative disorders. The role of genetic factors in its pathogenesis is supported by several lines of evidence: the high concordance in twins using PET scan; the increased risk among relatives of PD patients in case control and family studies; the existence of monogenic forms of PD. the alpha-synuclein gene is involved in a rare dominant form of the disease for which a new locus has been recently mapped to chromosome 2. Early onset autosomal recessive parkinsonism, which maps to chromosome 6q, appears to be frequent in Japan and in Europe. The genes for several monogenic forms of this entity should be identified soon, providing new insight into the pathophysiology of the disease. However, it is not clear if these genes will be relevant to apparently sporadic cases. In the long term, genotyping of affected sib-pairs should permit localisation and identification of other genetic susceptibility factors. These complementary approaches will contribute to the elucidation of the mechanism of PD and should provide new targets for drug therapies.