The beta-synuclein protein is highly homologous to the alpha-synuclein protein for which two mutations were reported in some familial cases of Parkinson disease. It has been shown that both alpha- and beta-synucleins may be able to inhibit phospholipase D2 selectively. We have observed that the beta-synuclein gene (HGMW-approved symbol, SNCB) is highly expressed in brain including the substantia nigra, the main region of neuronal degeneration in patients with Parkinson disease. We have determined the intron-exon structure of the beta-synuclein gene and established sequencing assays that will facilitate the search for mutations in the beta-synuclein gene in patients with Parkinson disease or other neurodegenerative disorders.