The Movement Disorders Division studies the genetic and environmental risk factors for a variety of degenerative diseases including Parkinson's disease (PD), essential tremor, and Huntington's disease. Several clinical trials and observational studies are ongoing.
Drs. Karen Marder, Lorraine Clark, and colleagues have examined several newly identified mutations associated in a unique sample of Parkinson's disease patients, half of whom were recruited because their symptoms began at or before the age of 50 (early onset) and half after 50 (late onset), and controls recruited by random digit dialing. We completely sequenced the parkin gene and looked for exon deletions and duplications. We found that 9.9 percent of 101 early-onset PD cases had mutations in the parkin gene, which is comparable to other studies of early-onset PD patients who do not report a family history of PD. Importantly, because of the ethnic diversity in our sample, we also showed that the frequency of a previously identified mutation (Leu261Leu) was similar in cases and controls, suggesting that this is not, in fact, a mutation. This study demonstrates the importance of examining purported mutations in various ethnic groups.