Parkinson's disease (PD) is the second most common neurodegenerative disorder after Alzheimer's disease, affecting approximately 1 percent of the population over age 50. Recent studies have confirmed significant familial aggregation of PD and a large number of large multicase families have been documented. Genetic markers on chromosome 4q21-q23 were found to be linked to the PD phenotype in a large kindred with autosomal dominant PD, with a Zmax = 6.00 for marker D4S2380. This finding will facilitate identification of the gene and research on the pathogenesis of PD.

We report the results of linkage analysis in a large American family of Czech descent with dominantly inherited "pure" essential tremor (ET) and genetic anticipation. Genetic loci on chromosome 2p22-p25 establish linkage to this region with a maximum LOD score (Zmax) = 5.92 for the locus, D2S272. Obligate recombinant events place the ETM gene in a 15-cM candidate interval between the genetic loci D2S168 and D2S224. Repeat expansion detection analysis suggests that expanded CAG trinucleotide sequences are associated with ET. These findings will facilitate the search for an ETM gene and may further our understanding of the human motor system.

No abstract