In the last decade, six monogenic forms of Parkinson disease (PD) have clearly been associated with this movement disorder. The identification of single genes linked to heritable forms of PD has revolutionized the previously held view of a largely nongenetic etiology. The most frequent and, thus, clinically most relevant forms are LRRK2- and PARKIN-associated PD. A main focus of present research is the investigation of the exact function of the genes and proteins involved in genetic PD to better understand the underlying pathophysiologic mechanisms of the much more common idiopathic form of the disorder. Neurologists are increasingly faced with the option of gene testing for PD. Unfortunately, these tests are expensive, do not predict the disease course in the individual patient, and rarely influence family planning. Currently, a positive test result does not change the choice of therapy, nor is any neuroprotective intervention available. However, genetic tests are useful in the basic and clinical research setting to identify at-risk individuals in whom preclinical changes and potential compensatory mechanisms can be elucidated and who may be candidates for neuroprotective trials.
Relationship Disclosure: Dr Lohmann has nothing to disclose. Dr Klein has received personal compensation for speaking engagements with GlaxoSmithKline PLC and Boehringer Ingelheim Pharmaceuticals, Inc.
Unlabeled Use of Products/Investigational Use Disclosure: Drs Lohmann and Klein have nothing to disclose.