G2385R Variant Research Articles

High-depth whole-genome sequencing identifies structure variants, copy number variants and short tandem repeats associated with Parkinson’s disease

While numerous single nucleotide variants and small indels have been identified in Parkinson’s disease (PD), the contribution of structural variants (SVs), copy number variants (CNVs), and short tandem repeats (STRs) remains poorly understood. Here we investigated the association using the high-depth whole-genome sequencing data from 466 Chinese PD patients and 513 controls. Totally, we identified 29,561 SVs, 32,153 CNVs, and 174,905 STRs, and found that CNV deletions were significantly enriched in the end-proportion of autosomal chromosomes in PD. After genome-wide association analysis and replication in an external cohort of 352 cases and 547 controls, we validated that the 1.6 kb-deletion neighboring MUC19, 12.4kb-deletion near RXFP1 and GGGAAA repeats in SLC2A13 were significantly associated with PD. Moreover, the MUC19 deletion and the SLC2A13 5-copy repeat reduced the penetrance of the LRRK2 G2385R variant. Moreover, genes with these variants were dosage-sensitive. These data provided novel insights into the genetic architecture of PD.

A 10-Year Community-Based Study of Leucine-Rich Repeat Kinase 2 G2385R Carriers' Conversion to Parkinson's Disease.

The G2385R variant of leucine-rich repeat kinase 2 (LRRK2) is mainly associated with Parkinson's disease(PD) in Asian populations. The aim of this study was to investigate the PD conversion rate and clinical characteristics of LRRK2 G2385R nonmanifesting carriers. All participants were from the community-based longitudinal cohort of Shanghai Ruijin Hospital. The G2385R carriers and noncarriers were screened by Sanger sequencing and received face-to-face interviews at baseline and follow-up assessments. The Kaplan-Meier method was used to compare the conversion rate of PD. Cox regression models were used to estimate the risk of G2385R variant for PD. In the combined cohort, 26 (7.9%) people developed PD in 329 carriers versus 9 (2.6%) in 345 noncarriers (P= 0.0016). Cox regression model confirmed that the G2385R variant was a strong risk factor for PD in a Chinese population older than 50 years (hazard ratio,3.314; 95% confidence interval,1.551-7.078; P= 0.002). No difference was found in clinical symptoms between carriers and noncarriers. We confirmed an increased conversion of PD in leucine-rich repeat kinase 2 G2385R carriers during a 10-year follow-up. © 2022 International Parkinson and Movement Disorder Society.

Penetrance of Parkinson disease LRRK2 G2385R-associated variant in the Chinese population.

Penetrance estimates of the leucine-rich repeat kinase 2 (LRRK2) variants for Parkinson disease (PD) vary widely. G2385R is one of the most common LRRK2 variants in Asian populations, and its penetrance is currently unknown. We aimed to estimate the penetrance of G2385R in the Chinese population. The G2385R variant was tested by Sanger sequencing in 6386 participants older than 50 years, all from the community cohort established by Shanghai Ruijin Hospital in 2009-2011. G2385R carriers and matched noncarriers underwent a brief questionnaire survey (including sex, current age, PD diagnosis, and age at onset) and face-to-face PD assessment during 2020-2021. The penetrance of PD was estimated by the Kaplan-Meier method. A total of 396 G2385R carriers and 415 noncarriers were included, after excluding those with a baseline diagnosis of PD or unwilling to participate. In G2385R carriers, the penetrance of PD was 1.64% at 70 years, 10.26% at 80 years, and 18.49% at 90 years, and reached 25.90% at 95 years. The penetrance of PD in G2385R carriers was higher than in noncarriers (p= 0.0071). In noncarriers, only 0%, 3.72%, and 9.66% developed parkinsonism by 70, 80, and 90 years of age. Among carriers and noncarriers, there were no statistically significant differences in penetrance comparisons between males and females, or between urban and rural. The lifetime penetrance of LRRK2 G2385R in the Chinese population was 25.9%. The penetrance modifier of G2385R in our study was age-related. Further investigation of genetic and environmental modifiers affecting G2385R penetrance is warranted.

Accelerated telomere shortening independent of LRRK2 variants in Chinese patients with Parkinson's disease.

Oxidative stress and inflammation play vital roles in Parkinson’s disease (PD) development. Thus, telomere length is expected to be shortened in this disease, but current data are inconclusive. We performed a case-control study of 261 patients with PD and 270 sex and age-matched healthy controls treated at the Peking Union Medical College Hospital. We found leucocyte telomere length (LTL) was significantly shortened in PD as compared with controls [1.02 (0.84-1.39) vs. 1.48 (1.08-1.94), P<0.001] and shorter LTL was associated with a dramatically increased risk of PD (lowest vs. highest quartile odds ratio (OR) =9.54, 95% CI: 5.33-17.06, P<0.001). We also investigated the roles of six LRRK2 variants in the susceptibility to PD. R1441C/G/H, G2019S, and I2020T variations were not detected in our study. No significant differences were found in the presence of variants R1398H (15.4% vs. 17.0%, P=0.619) and R1628P (2.3% vs. 0.7%, P=0.159) in PD and controls, while the G2385R variant was found to be a risk factor associated with increased PD susceptibility (OR=2.14, 95% CI: 1.12-4.10, P=0.021). No significant association was found between different LRRK2 variants and telomere length. These findings suggest that shorter LTL might be associated with PD in a manner independent of LRRK2 variants.

Effect of LRRK2 G2385R Variant on Subthalamic Deep Brain Stimulation Efficacy in Parkinson's Disease in a Han Chinese Population

Deep brain stimulation (DBS) of the subthalamic nucleus (STN) is an effective treatment for advanced Parkinson's disease (PD). The G2385R variant of LRRK2 is a risk factor for PD in Han Chinese individuals. We retrospectively compared the clinical outcomes of STN-DBS surgery between PD Han Chinese G2385R variant carriers and non-carriers. Fifty-seven PD patients with bilateral STN-DBS were enrolled, including 8 G2385R+ variant carriers (G2385R+ group) and 49 non-carriers (G2385R– group). Clinical data included Unified Parkinson's Disease Rating Scale (UPDRS) parts I to IV, levodopa equivalent daily dose (LEDD), Mini-Mental State Examination Scale (MMSE) score, and Hamilton Depression Rating Scale (HAMD) score measured prior to DBS and 12 months post-DBS. DBS settings were also recorded. All PD patients benefited from STN-DBS surgery. There were no statistical differences between the two groups in terms of motor function, daily living activities, and LEDD reductions at 12 months post-DBS. The rigidity of the post-surgical G2385R+ group was significantly improved compared with that of the G2385R– group (P = 0.045). Post-surgical voltage in the G2385R+ group was significantly higher than that in the G2385R– group (P = 0.033). STN-DBS outcomes were not influenced by the LRRK2 G2385R variant in Han Chinese patients.

Gender differences in prevalence of LRRK2-associated Parkinson disease: A meta-analysis of observational studies

BackgroundThe gender effect in the prevalence of leucine-rich repeat kinase 2 (LRRK2) associated Parkinson disease (PD) remains controversial. Herein, we conducted a meta-analysis to investigate the gender effect among these patients. MethodsPubMed and EMBASE databases were searched to identify the potential related studies published before December 2017. Case-control studies with separated data of sex and mutation status were included in further analyses. We pooled relative risk (RR) using fixed-effect model. The publication bias and sensitivity analyses were also performed. ResultsSixty-four studies with 32452 patients diagnosed with PD were included. Higher prevalence of female patients with LRRK2-associated PD was observed with a pooled RR of 1.22 (95% CI 1.14–1.30, P＜0.001). Further subgroup analyses showed that higher prevalence of female patients was only obtained in G2019S mutation patients (RR = 1.32, 95% CI 1.23–1.43, P＜0.001), but not in G2385R variant patients (RR = 1.03, 95% CI 0.91–1.17, P = 0.651). No significant heterogeneity and publication bias were observed in additional analyses. ConclusionsHigher female prevalence of LRRK2 mutation suggests roles of gender-related risk factors in PD patients, especially who carried G2019S mutation. Contrary to idiopathic PD, no sex difference was observed in prevalence of patients carried G2385R variant.

Prevalence of pre-diagnostic symptoms did not differ between LRRK2-related, GBA-related and idiopathic patients with Parkinson's disease

IntroductionGlucocerebrosidase (GBA) mutations and leucine-rich repeat kinase 2 (LRRK2) variants are the most common genetic risk factors for late-onset Parkinson's disease (PD). In this study, we aimed to investigate the differences in pre-diagnostic symptoms of PD associated with the variants. MethodsThe participants were recruited from 24 centers across China and genotyped for LRRK2 G2385R and R1628P variants and GBA L444P mutation. Participants were surveyed with structural questionnaires for history of environmental exposure and living habits and interviewed to collect the time at onset of each symptoms before diagnosis. We compared the cumulative prevalence and manifestation pattern of symptoms between groups using multiple logistic regression, adjusting age and gender. ResultsTotal 1799 PD patients were recruited, including 226 patients with LRRK2 G2385R or R1628P variant, 44 with GBA L444P mutation, three with both LRRK2 and GBA mutation, and 1526 idiopathic patients. The cumulative prevalence of non-motor and typical motor symptoms did not differ between groups before diagnosis (P > 0.05). The manifestation sequences of non-motor symptoms were indistinguishable between the LRRK2-carriers, GBA-carriers, and idiopathic PD subjects, and followed the sequence of constipation, hyposmia, sleep disorders, anxiety and depression, sexual dysfunction, urinary incontinency, dizziness and cognition. Slightly higher prevalence of hypomimia and micrographia were detected in the GBA-carriers. ConclusionsThe prevalence of pre-diagnostic symptoms is almost indistinguishable between the LRRK2-carriers, GBA-carriers, and idiopathic PD before diagnosis; the sequence of the manifestation of non-motor symptoms largely conforms to the Braak stage for both genetic-related and idiopathic late-onset PD.

The Association between LRRK2 G2385R and Phenotype of Parkinson's Disease in Asian Population: A Meta-Analysis of Comparative Studies.

Numerous studies have investigated the relationship between the LRRK2 G2385R variant and clinical characteristics in Parkinson's disease (PD), but the results have been inconsistent. This study investigated whether the LRRK2 G2385R variant was associated with a unique clinical phenotype of PD in the Asian population, using a meta-analysis. The PubMed, Web of Science, EMBASE, CNKI, and WANFANG databases were searched until September 2017. The strict selection criteria and exclusion criteria were determined, and mean differences (MD) or odds ratios (OR) with 95% confidence intervals (CI) were used to assess the strength of associations. Statistical analyses and graphics were performed using Review Manager 5.3. Sixteen related case-control studies were included in the meta-analysis. The LRRK2 G2385R carriers significantly more often presented a family history (OR: 1.98; 95% CI: 1.16−3.39; P=0.01) and had a longer disease duration (MD = 0.47, 95% CI: 0.01−0.93, P=0.04) and a higher MMSE score (MD = 1.02, 95% CI: 0.43–1.62 P=0.0007) than LRRK2 G2385R noncarriers. There were no significant differences in sex distribution, age at onset, initial symptoms, motor symptoms, depression, levodopa-equivalent dose, and related complications between LRRK2 G2385R-carrier and LRRK2 G2385R-noncarrier PD patients. Our results suggested that most of the clinical characteristics of PD patients with LRRK2 G2385R mutations are similar to those of LRRK2 G2385R noncarriers among Asian PD patients, except for the more common family history, relatively longer disease duration, and higher MMSE scores in the former group.

Generation of 2 induced pluripotent stem cell lines derived from patients with Parkinson's disease carrying LRRK2 G2385R variant

Leucine rich repeat kinase (LRRK2) is the most prevalent genetic cause for Parkinson's disease. LRRK2 p.G2385R is an Asian specific genetic risk factor for sporadic Parkinson's disease. We generated two induced pluripotent stem cells (iPSCs), IBMS-iPSC-018-09 and IBMS-iPSC-020-01, from the peripheral blood mononuclear cells of two patients carrying LRRK2 p.G2385R variant by using the Sendai-virus delivery system. These iPSCs had a normal karyotype and exhibited pluripotency, such as an embryonic stem cell-like morphology, expression of pluripotent markers, and capacity to differentiate into three germ layers. This cellular model will provide a platform for pathophysiological studies of neurodegeneration in Parkinson's disease.

Fatigue correlates with LRRK2 G2385R variant in Chinese Parkinson's disease patients

IntroductionFatigue is common in patients with Parkinson's disease (PD). The leucine-rich repeat kinase 2 (LRRK2) G2385R variant predisposes individuals to develop PD in China. The aim of this study was to evaluate whether the LRRK2 G2385R variant is associated with fatigue in patients with PD. MethodsFatigue was evaluated by the Parkinson Fatigue Scale (PFS) in 329 PD patients and 180 controls, a cut-off score of ≥3.3 was used to define the presence of fatigue. All the enrolled PD patients were assessed by a comprehensive battery of motor and non-motor questionnaires. PD patients were genotyped for the G2385R variant. Associations of fatigue with the clinical assessments and with the G2385R variant in PD patients were analyzed by logistic regression. ResultsFatigue frequency was 55.62%. A logistic regression model found that the female sex (OR = 10.477; 95%CI: 2.806–39.120; p < 0.001), motor function (OR = 1.060; 95%CI: 1.012–1.110; p = 0.013), sleep disturbance (OR = 0.943; 95%CI: 0.910–0.976; p = 0.001) and depression severity (OR = 0.843; 95%CI: 0.736–0.965; p = 0.013) collectively predict the presence of fatigue in PD patients. After adjustment for demographics and associated clinical factors, the G2385R variant was associated with an increased risk for the presence of fatigue (OR = 10.699; 95% CI = 2.387–47.958; p = 0.002) in the PD population in this study. ConclusionWe confirm that fatigue in PD patients is common, and we have strengthened the associations between fatigue and female sex, motor severity and non-motor symptoms, particularly depression and sleep disturbances. Overall, we found that carriers of the G2385R variant were more prone to fatigue than non-carriers in PD patients.

The LRRK2 G2385R variant is a partial loss-of-function mutation that affects synaptic vesicle trafficking through altered protein interactions

Mutations in the Leucine-rich repeat kinase 2 gene (LRRK2) are associated with familial Parkinson’s disease (PD). LRRK2 protein contains several functional domains, including protein-protein interaction domains at its N- and C-termini. In this study, we analyzed the functional features attributed to LRRK2 by its N- and C-terminal domains. We combined TIRF microscopy and synaptopHluorin assay to visualize synaptic vesicle trafficking. We found that N- and C-terminal domains have opposite impact on synaptic vesicle dynamics. Biochemical analysis demonstrated that different proteins are bound at the two extremities, namely β3-Cav2.1 at N-terminus part and β-Actin and Synapsin I at C-terminus domain. A sequence variant (G2385R) harboured within the C-terminal WD40 domain increases the risk for PD. Complementary biochemical and imaging approaches revealed that the G2385R variant alters strength and quality of LRRK2 interactions and increases fusion of synaptic vesicles. Our data suggest that the G2385R variant behaves like a loss-of-function mutation that mimics activity-driven events. Impaired scaffolding capabilities of mutant LRRK2 resulting in perturbed vesicular trafficking may arise as a common pathophysiological denominator through which different LRRK2 pathological mutations cause disease.

Olfactory Dysfunction in Parkinson's Disease Patients with the LRRK2 G2385R Variant.

Olfactory dysfunction has been reported in Parkinson's disease (PD) patients carrying the LRRK2 G2019S variant in Caucasians but rarely in those with the LRRK2 G2385R variant. In this study, we performed genotyping for the LRRK2 G2385R variant in PD patients recruited from the Movement Disorder Clinic of Xuanwu Hospital in Beijing and in healthy controls randomly selected from the Beijing Longitudinal Study on Aging cohort. The "five-odor olfactory detection array", an olfactory threshold test, was used to assess olfactory function. One hundred and eighty-six participants were enrolled, comprising 43 PD patients without (iPD) and 25 with (LRRK2-PD) the LRRK2 G2385R variant, and 118 healthy controls. Our results showed that the threshold of olfactory identification was significantly worse in PD patients than in controls, but not significantly different between the iPD and LRRK2-PD groups. These findings suggested that although olfactory function in LRRK2-PD patients is impaired, it is similar to that in iPD patients.

Effect of a Leucine-rich Repeat Kinase 2 Variant on Motor and Non-motor Symptoms in Chinese Parkinson's Disease Patients.

The G2385R variant of the leucine-rich repeat kinase 2 (LRRK2) is strongly associated with Parkinson’s disease (PD) in Asian populations. However, it is still unclear whether the clinical phenotype of PD patients with the G2385R variant can be distinguished from that of patients with idiopathic PD. In this study, we investigated motor and non-motor symptoms of LRRK2 G2385R variant carriers in a Chinese population. We genotyped 1031 Chinese PD patients for the G2385R variant of the LRRK2 gene, and examined the demographic and clinical characteristics of LRRK2 G2385R variant carrier and non-carrier PD patients. LRRK2 G2385R variant carriers were more likely to present the postural instability and gait difficulty dominant (PIGD) phenotype. This variant was also significantly associated with motor fluctuations and the levodopa equivalent dose (LED). G2385R variant carriers had higher REM sleep behavior disorder (RBD) screening questionnaire (RBDSQ) score and more RBD symptoms compared with non-carriers. We concluded that the G2385R variant could be a risk factor for the PIGD phenotype, motor fluctuations, LED values and RBD symptoms.

LRRK2 modulates neuronal vesicles cycle through protein interactions

Mutations in Leucine-rich repeat kinase 2 gene (LRRK2) are associated with familial and sporadic Parkinson’s disease (PD). LRRK2 is a complex protein that consists of multiple domains executing several functions, including GTP hydrolysis, kinase activity and a C-terminal WD40 domain devoted to protein binding. Robust evidence suggests that LRRK2 acts at the synaptic site as a molecular hub connecting synaptic vesicles to cytoskeletal elements via a complex panel of protein-protein interactions. We have investigated the impact of pharmacological inhibition of LRRK2 kinase activity on synaptic function. Acute treatment with LRRK2 inhibitors reduced the frequency of spontaneous currents, the rate of synaptic vesicle trafficking and the release of neurotransmitter from isolated synaptosomes. The investigation of complementary models lacking LRRK2 expression allowed us to exclude potential off-side effects of kinase inhibitors on synaptic functions. Next we studied whether kinase inhibition affects LRRK2 heterologous interactions. We found that the binding among LRRK2, presynaptic proteins and synaptic vesicles is affected by kinase inhibition. Interestingly, a sequence variant (G2385R) within the WD40 domain has been implicated as a risk factor in PD, but its physiological and pathological function has not been systematically addressed yet. We analyzed molecular features of the WD40 domain and we addressed the functional implication of the G2385R variant. Our results suggest that LRRK2 WD40 domain serves as a hub for protein interactions setting LRRK2 as part of a protein network involved in synaptic vesicle trafficking. Furthermore we showed that the G2385R mutation influences WD40 domain features in terms of domain folding and binding properties and has an impact on synaptic vesicle dynamic. Our results suggest that different PD mutation might influence synaptic vesicle release via modulation of LRRK2 macro-molecular complex.

The association between the LRRK2 G2385R variant and the risk of Parkinson's disease: a meta-analysis based on 23 case-control studies.

Clinical diagnosis of Parkinson's disease (PD) is essential but misdiagnosis of PD-like diseases is quite common. LRRK2 G2385R variants have been extensively examined for the association to the risk of Parkinson's disease. However, results from different studies are inconsistent. The purpose of this meta-analysis was to assess the association between the LRRK2 G2385R variants and the risk of PD. A systematic literature search was performed for 6 databases up to January of 2014 to identify case-control studies involving LRRK2 G2385R variants and the risk of PD. A total of 12,915 cases and 12,451 controls in 23 case-control studies were included in this meta-analysis. The results indicated that the variant A allele carriers (GA + AA) increased risk of PD when compared with the homozygote GG (GA + AA vs. GG: OR = 2.4, 95 % CI = 1.97 to 2.92, P < 0.00001). In the subgroup analysis by ethnicity, increased risks were identified among Chinese (OR = 2.69, 95 % CI = 2.1-3.45, P < 0.00001) as well as in non-Chinese (OR = 2.17, 95 % CI 1.75-2.69, P < 0.00001). In the subgroup analysis by age of onset, significant associations were found in both later-onset PD (LOPD) and early-onset PD (EOPD) cases. And there was no significant difference of the allele frequency between patients with LOPD and EOPD (OR = 1.18, 95 % CI = 0.77-1.80, P = 0.45). Our results suggest that the LRRK2 G2385R variants contribute to the susceptibility of PD especially in Chinese PD. Meanwhile, it is possible that age is not the risk factor to facilitate G2385R gene mutation.

LRRK2 G2385R variant carriers of female Parkinson’s disease are more susceptible to motor fluctuation

The relation between the LRRK2 mutation and its effect on Parkinson's disease (PD) has always caught a lot attention. Recent studies found that the G2385R polymorphism of LRRK2 may increase the risk of PD in Asian populations. Here we tried to clarify the relationship between the LRRK2 G2385R variant and the clinical profiles including motor complication in Chinese PD patients. We identified the LRRK2 variant in the Chinese Han population in northern China and evaluated the relationship between the G2385R variant and clinical profiles through comparison between 36 carriers and 139 non-carriers. We found that G2385R carriers scored significantly higher in motor fluctuation and dyskinesia than non-carriers. Logistic regression analysis showed that the G2385R variant was an independent risk factor for motor fluctuation in females (odds ratio=12.538, 95% CI2.216-70.942, P=0.004), and a Chi-squared test showed that the frequency of dyskinesia tended to be higher in the carrier group compared to the non-carrier group (16 vs. 4.4%, P=0.050, OR=4.127, 95% CI1.074-15.864). These findings indicate that the variant was closely related to the occurrence of motor complication. Additionally, the G2385R variant was significantly related to the early-onset of PD in female carriers (20.0 vs. 1.5%, odds ratio=16.25, 95% CI 1.557-169.618, P=0.020). Our study found that the G2385R variant was significantly associated with motor complications and that this variant was an independent risk factor for motor fluctuation in females. These findings provide the necessary preliminary data to better understand the unique profile of PD G2385R variant carriers.

Association between G2385R and R1628P polymorphism of LRRK2 gene and sporadic Parkinson’s disease in a Han-Chinese population in south-eastern China

The G2385R and R1628P polymorphisms of the leucine-rich repeat kinase 2 (LRRK2) gene have been reported to be associated with Parkinson's disease (PD), but no data are available on Han-Chinese population of south-eastern China. This study aimed to investigate whether G2385R and R1628P variants are associated with sporadic PD in this population. Total 1,060 subjects were enrolled; including 550 unrelated healthy controls and 510 patients with sporadic PD. Genotyping of polymorphisms was performed by PCR-restriction fragment length polymorphism analysis. All variant samples were sequenced for further confirmation. The results showed that the A allele of the G2385R variant was significantly enriched in sporadic PD patient group (4.8%) when compared with control group [1.1%; odds ratio (OR) 4.58, 95% confidence interval (CI) 2.42-8.65, P < 0.01]. However, no significant difference in the frequency of the C allele of R1628P polymorphism variant was observed between cases and controls (2.8 vs. 1.7%, OR 1.67, 95% CI 0.93-2.99, P = 0.08). In conclusion, this study provides the first evidence that G2385R polymorphism is a risk factor for sporadic PD in Han-Chinese population of south-eastern China.

The LRRK2 R1628P Variant Plays a Protective Role in Han Chinese Population with Alzheimer's Disease

Alzheimer's disease (AD) and Parkinson's disease (PD) are the most prevalent neurodegenerative disorders that may share some overlapping etiologies. Mutations within leucine-rich repeat kinase 2 (LRRK2) have been reported to be responsible for PD, and the location of LRRK2 is within a linkage peak for sporadic AD (SAD). The aim of this study was to investigate two Asian-specific LRRK2 variants, R1628P and G2385R, with the association of Han Chinese SAD. Genotyping of R1628P and G2385R was performed by PCR-restriction fragment length polymorphism (RFLP) analysis in 390 patients with SAD and 545 unrelated age- and sex-matched healthy controls. The frequency of the C allele within R1628P was more than three times higher in control group (1.7%) than in patients with SAD (0.5%) (OR 0.264; 95% CI, 0.088-0.792, P = 0.018). After stratification by the presence of one or two apolipoprotein E ε4 alleles, the protective effect becomes stronger (ε44: OR 0.028; 95% CI, 0.003-0.303, P = 0.003; ε4: OR 0.104; 95% CI, 0.013-0.818, P = 0.031). However, no difference was found in G2385R variant. Our study suggested that R1628P variant within LRRK2 plays a protective role in Han Chinese population with SAD and such effect has an interaction with the APOE genotype.

A case of α‐synuclein gene duplication presenting with head‐shaking movements

PARK4 is a candidate locus for familial Parkinson's disease (PD), combined with multiplication of the α-synuclein gene (SNCA). The eventual phenotype is dependent on the copy number of SNCA. Mutations in leucine-rich repeat kinase 2 (LRRK2) are also causative of parkinsonism. This report describes a man who presented at our hospital complaining of a stagger after running and difficulty in handling the mouse of a personal computer, having suffered tremors since his twenties. Nine months after treatment and discharge, he developed titubation and began to drag his right foot. We examined the patient's family pedigree for SNCA dosage, using quantitative polymerase chain reaction. We also screened this pedigree for mutations in parkin and LRRK2, using gene-sequencing techniques. We identified the proband, his sister, and his paternal uncle as carrying a duplication of SNCA. In addition, we found that the proband and his mother carried the G2385R variant of the LRRK2, a strong risk factor for PD in Asians and the rare V1450I variant, although only the proband showed symptoms of parkinsonism. No mutations were found in parkin. The combination of SNCA gene duplication and LRRK2 G2385R variant may explain the early onset of disease in this patient.

The G2385R variant of leucine-rich repeat kinase 2 associated with Parkinson's disease is a partial loss-of-function mutation

Autosomal-dominant missense mutations in LRRK2 (leucine-rich repeat kinase 2) are a common genetic cause of PD (Parkinson's disease). LRRK2 is a multidomain protein with kinase and GTPase activities. Dominant mutations are found in the domains that have these two enzyme activities, including the common G2019S mutation that increases kinase activity 2-3-fold. However, there is also a genetic variant in some populations, G2385R, that lies in a C-terminal WD40 domain of LRRK2 and acts as a risk factor for PD. In the present study we show that the G2385R mutation causes a partial loss of the kinase function of LRRK2 and deletion of the C-terminus completely abolishes kinase activity. This effect is strong enough to overcome the kinase-activating effects of the G2019S mutation in the kinase domain. Hsp90 (heat-shock protein of 90 kDa) has an increased affinity for the G2385R variant compared with WT (wild-type) LRRK2, and inhibition of the chaperone binding combined with proteasome inhibition leads to association of mutant LRRK2 with high molecular mass native fractions that probably represent proteasome degradation pathways. The loss-of-function of G2385R correlates with several cellular phenotypes that have been proposed to be kinase-dependent. These results suggest that the C-terminus of LRRK2 plays an important role in maintaining enzymatic function of the protein and that G2385R may be associated with PD in a way that is different from kinase-activating mutations. These results may be important in understanding the differing mechanism(s) by which mutations in LRRK2 act and may also have implications for therapeutic strategies for PD.