Screening for mutations in synaptotagmin XI in Parkinson's disease.

Parkinson's disease (PD) is characterized by selective degeneration of neurons in the substantia nigra and subsequent dysfunction of dopaminergic neurotransmission. Genes identified in familial forms of PD encode proteins that are linked to the ubiquitin-proteasome system indicating the pathogenic relevance of disturbed protein degradation in PD. Some of them, i.e. alpha-synuclein, parkin and synphilin-1, have been implicated in presynaptic neurotransmission based on their localization in synaptic vesicles. Synaptotagmin XI is linked to the pathogenesis of PD based on its identification as a substrate of the ubiquitin-E3-ligase parkin. Moreover synaptotagmin XI is involved in the maintainance of synaptic function and represents a component of Lewy bodies (LB) in brains of PD patients. Therefore, we performed a detailed mutation analysis of the synaptotagmin XI gene in a large sample of 393 familial and sporadic PD patients. We did not find any disease causing mutations arguing against a major role of mutations in the synaptotagmin XI gene in the pathogenesis of PD.