Common genetic variants that increase the risk for Parkinson's disease may differentiate patient subgroups and influence future individualized therapeutic strategies. Herein we show evidence for leucine-rich repeat kinase 2 (LRRK2) c.4883G>C (R1628P) as a risk factor in ethnic Chinese populations. A study of 1,986 individuals from 3 independent centers in Taiwan and Singapore demonstrates that Lrrk2 R1628P increases risk for Parkinson's disease (odds ratio, 1.84; 95% confidence interval, 1.20-2.83; p = 0.006). Haplotype analysis suggests an ancestral founder for carriers approximately 2,500 years ago. These findings support the importance of LRRK2 variants in sporadic Parkinson's disease. Ann Neurol 2008.

We and others found two polymorphic LRRK2 (leucine-rich repeat kinase 2) variants (rs34778348:G>A; p.G2385R and rs33949390:G>C; p.R1628P) associated with Parkinson disease (PD) among Chinese patients, but the common worldwide rs34637584:G>A; p.G2019S mutation, was absent. Focusing exclusively on Han Chinese, we first sequenced the coding regions in young onset and familial PD patients and identified 59 variants. We then examined these variants in 250 patients and 250 control subjects. Among the 17 polymorphic variants, five demonstrated different frequency in cases versus controls and were considered in a larger sample of 1,363 patients and 1,251 control subjects. The relative risk of an individual with both p.G2385R and p.R1628P is about 1.9, and this is reduced to 1.5-1.6 if the individual also carries rs7133914:G>C; p.R1398H or rs7308720:C>A: p.N551K. The risk of a carrier with p.R1628P is largely negated if the individual also carries p.R1398H or p.N551K. In dopaminergic neuronal lines, p.R1398H had significantly lower kinase activity, whereas p.G2385R and p.R1628P showed higher kinase activity than wild type. We provided the first evidence that multiple LRRK2 variants exert an individual effect and together modulate the risk of PD among Chinese.

Morphine loses analgesic potency after repeated administration. The underlying mechanism is not fully understood. Glia are thought to be involved in morphine tolerance, and P2X 7 purinergic receptor (P2X 7 R) has been implicated in neuron-glia communication and chronic pain. The present study demonstrated that P2X 7 R immunoreactivity was colocalized with the microglial marker OX42, but not the astrocytic marker GFAP, in the spinal cord. The protein level of spinal P2X 7 R was upregulated after chronic exposure to morphine. Intrathecal administration of Brilliant Blue G (BBG), a selective P2X 7 R inhibitor, significantly attenuated the loss of morphine analgesic potency, P2X 7 R upregulation, and microglial activation. Furthermore, RNA interference targeting the spinal P2X 7 R exhibited a similar tolerance-attenuating effect. Once morphine analgesic tolerance is established, it was no longer affected by intrathecal BBG. Together, our results suggest that spinal P2X 7 R is involved in the induction but not maintenance of morphine tolerance.

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Background Recent genetic progress has allowed for the molecular diagnosis of Parkinson's disease. However, genetic causes of PD vary widely in different ethnicities. Mutational frequencies and clinical phenotypes of genes associated with PD in Asian populations are largely unknown. The objective of this study was to identify the mutational frequencies and clinical spectrums of multiple PD‐causative genes in a Taiwanese PD cohort. Methods A total of 571 participants including 324 patients with early‐onset parkinsonism (onset age, <50 years) and 247 parkinsonism pedigrees were recruited at a tertiary referral center in Taiwan from 2002 to 2017. Genetic causes were identified by an integrated approach including gene dosage analysis, a targeted next‐generation sequencing panel containing 40 known PD‐causative genes, repeat‐primed polymerase chain reaction, and whole‐exome sequencing analysis. Results Thirty of the 324 patients with early‐onset parkinsonism (9.3%) were found to carry mutations in Parkin , PINK1 , or PLA2G6 or had increased trinucleotide repeats in SCA8 . Twenty‐nine of 109 probands with autosomal‐recessive inheritance of parkinsonism (26.6%) were found to carry mutations in Parkin , PINK1 , GBA , or HTRA2 . The genetic causes for the 138 probands with an autosomal‐dominant inheritance pattern of parkinsonism were more heterogeneous. Seventeen probands (12.3%) carried pathogenic mutations in LRRK2 , VPS35 , MAPT , GBA , DNAJC13 , C9orf72 , SCA3, or SCA17 . A novel missense mutation in the UQCRC1 gene was found in a family with autosomal‐dominant inheritance parkinsonism via whole‐exome sequencing analysis. Conclusions Our findings provide a better understanding of the genetic architecture of PD in eastern Asia and broaden the clinical spectrum of PD‐causing mutations. © 2019 The Authors. Movement Disorders published by Wiley Periodicals, Inc. on behalf of International Parkinson and Movement Disorder Society.