High-resolution arrays reveal burden of copy number variations on Parkinson disease genes associated with increased disease risk in random cohorts

Background: Parkinson disease (PD) is a neurological disease responsible for a considerable rate of mortality and morbidity in the society. Since the symptoms of the disease appear much later than the actual onset of neuron degeneration, a majority of cases remain undiagnosed until the manifestation of the symptoms. Objectives: In order to investigate the existence of such susceptibility in the population, we analyzed Copy Number Variation (CNV) influences on PD genes in 1715 individuals from 12 different populations. Results: Overall, 16 CNV-PD genes, 3 known to be causal and 13 associated, were found to be significantly enriched. PARK2, was under heavy burden with similar to 1% of the population containing CNV in the exonic region. The impact of these genes on the genome and disease pathway was analyzed using several genome analysis tools. Protein interaction network of CNV-PD genes revealed a complex interaction of molecules forming a major hub by the alpha-Synuclein, whose direct interactors, LRRK2, PARK2 and ATP13A2 are under CNV influence. Conclusions: We hypothesize that CNVs may not be the initiating event in the pathogenesis of PD and remain latent until additional secondary hits are acquired and also propose novel genes that may fall under the PD pathway which contribute in pathogenesis.