Familial Aggregation of Essential Tremor and Parkinson's Disease (PD4.004)

Abstract

Objective: To inspect the co-occurrence of essential tremor (ET) and Parkinson9s disease (PD) in families and evaluate their clinical and genetic characteristics. Background ET and PD are two separate entities and both disorders are common. Thus their coexistence could be due to chance effect. However, their presence within the same family suggests potential overlap in genetic predisposition. There are also reports suggesting the possibility of a pathogenic link between these two conditions. Design/Methods: We reviewed the Mayo Clinic Florida Familial Movement Disorder database for ET and PD cases with blood samples collected. We isolated families with members diagnosed with ET, PD or both conditions within the same individual. We also performed mutation analysis of all known pathogenic mutations in the LRRK2 gene within these familial cases. Results: We identified 286 ET and 1033 PD cases from our database. We found 131 families with members affected by both ET and PD. There were 37 families having 43 individuals afflicted with both conditions. On examination postural and kinetic tremor affecting hands, voice, head or combination of these was seen. Cardinal symptoms of PD were also found, including resting tremor, bradykinesia, rigidity, and impaired postural reflexes. In 37 cases, 23 individuals showed signs of ET preceding the onset of PD whereas four cases were diagnosed with PD prior to ET. Five patients were diagnosed with ET and PD simultaneously and information was not available for 11 other individuals. Genetic tests revealed that all samples were negative for known LRRK2 pathogenic mutations. Conclusions: We plan to investigate these families using further genetic approaches in order to learn about the molecular genetic makeup of ET and PD. Supported by: ZKW is partially supported by the NIH/NINDS 1RC2NS070276, NS057567, P50 NS072187-01S2, Mayo Clinic Florida (MCF) Research Committee CR program (MCF #90052030), Dystonia Medical Research Foundation, and the gift from Carl Edward Bolch, Jr., and Susan Bass Bolch (MCF #90052031/PAU #90052). SF is partially supported by MCF Research Committee CR program (MCF #90052030). Disclosure: Dr. Fujioka has nothing to disclose. Dr. Hanna AL-Shaikh has nothing to disclose. Dr. Sundal has nothing to disclose. Dr. Strongosky has nothing to disclose. Dr. Ross has nothing to disclose. Dr. Wszolek has received personal compensation in an editorial capacity for Parkinsonism and Realted Disorders and European Journal of Neurology.