Targeted sequencing of Parkinson's disease loci genes highlights SYT11, FGF20 and other associations.

Genome-wide association studies (GWAS) have identified numerous loci associated with Parkinson's disease. The specific genes and variants that drive the associations within the vast majority of these loci are unknown. We aimed to perform a comprehensive analysis of selected genes to determine the potential role of rare and common genetic variants within these loci. We fully sequenced 32 genes from 25 loci previously associated with Parkinson's disease in 2657 patients and 3647 controls from three cohorts. Capture was done using molecular inversion probes targeting the exons, exon-intron boundaries and untranslated regions (UTRs) of the genes of interest, followed by sequencing. Quality control was performed to include only high-quality variants. We examined the role of rare variants (minor allele frequency < 0.01) using optimized sequence Kernel association tests. The association of common variants was estimated using regression models adjusted for age, sex and ethnicity as required in each cohort, followed by a meta-analysis. After Bonferroni correction, we identified a burden of rare variants in SYT11, FGF20 and GCH1 associated with Parkinson's disease. Nominal associations were identified in 21 additional genes. Previous reports suggested that the SYT11 GWAS association is driven by variants in the nearby GBA gene. However, the association of SYT11 was mainly driven by a rare 3' UTR variant (rs945006601) and was independent of GBA variants (P = 5.23 × 10-5 after exclusion of all GBA variant carriers). The association of FGF20 was driven by a rare 5' UTR variant (rs1034608171) located in the promoter region. The previously reported association of GCH1 with Parkinson's disease is driven by rare non-synonymous variants, some of which are known to cause dopamine-responsive dystonia. We also identified two LRRK2 variants, p.Arg793Met and p.Gln1353Lys, in 10 and eight controls, respectively, but not in patients. We identified common variants associated with Parkinson's disease in MAPT, TMEM175, BST1, SNCA and GPNMB, which are all in strong linkage disequilibrium with known GWAS hits in their respective loci. A common coding PM20D1 variant, p.Ile149Val, was nominally associated with reduced risk of Parkinson's disease (odds ratio 0.73, 95% confidence interval 0.60-0.89, P = 1.161 × 10-3). This variant is not in linkage disequilibrium with the top GWAS hits within this locus and may represent a novel association. These results further demonstrate the importance of fine mapping of GWAS loci, and suggest that SYT11, FGF20, and potentially PM20D1, BST1 and GPNMB should be considered for future studies as possible Parkinson's disease-related genes.

Analysis of Heterozygous PRKN Variants and Copy-Number Variations in Parkinson's Disease.

BACKGROUND: Biallelic PRKN mutation carriers with Parkinson's disease (PD) typically have an earlier disease onset, slow disease progression, and, often, different neuropathology compared to sporadic PD patients. However, the role of heterozygous PRKN variants in the risk of PD is controversial. OBJECTIVES: Our aim was to examine the association between heterozygous PRKN variants, including single-nucleotide variants and copy-number variations (CNVs), and PD. METHODS: We fully sequenced PRKN in 2809 PD patients and 3629 healthy controls, including 1965 late-onset (63.97 ± 7.79 years, 63% men) and 553 early-onset PD patients (43.33 ± 6.59 years, 68% men). PRKN was sequenced using targeted next-generation sequencing with molecular inversion probes. CNVs were identified using a combination of multiplex ligation-dependent probe amplification and ExomeDepth. To examine whether rare heterozygous single-nucleotide variants and CNVs in PRKN are associated with PD risk and onset, we used optimized sequence kernel association tests and regression models. RESULTS: We did not find any associations between all types of PRKN variants and risk of PD. Pathogenic and likely-pathogenic heterozygous single-nucleotide variants and CNVs were less common among PD patients (1.52%) than among controls (1.8%, false discovery rate-corrected P = 0.55). No associations with age at onset and in stratified analyses were found. CONCLUSIONS: Heterozygous single-nucleotide variants and CNVs in PRKN are not associated with PD. Molecular inversion probes allow for rapid and cost-effective detection of all types of PRKN variants, which may be useful for pretrial screening and for clinical and basic science studies targeting specifically PRKN patients. © 2020 International Parkinson and Movement Disorder Society.

Knowledge of and interest in genetic results among Parkinson disease patients and caregivers.

The purpose of the study is to investigate Parkinson disease (PD) patients' and caregivers' knowledge of and interest in genetic testing. Gaucher disease (GD) results from recessive mutations in glucocerebrosidase (GBA). Both heterozygote GBA carriers and GD patients are at greater risk for PD. Studies regarding knowledge of and interest in genetic testing have been limited and have not offered genetic results to participants. In this study, 353 PD patients and 180 caregivers were recruited to a PD genetic study. The association between GD, GBA mutations and PD was described to participants who reported their familiarity with genetic terms, answered questions on genetic concepts, and indicated their interest in knowing if they may have GD (two GBA mutations) and other genetic information that could impact their health. Ninety-three-percent of participants were interested in receiving GBA results; however, only 51.6 % of PD participants and 55.6 % of caregivers knew that "scientists have identified genes associated with a higher risk of developing PD." PD patients may benefit from education and genetic counseling on the implications of genetic testing.

The Clinical Development of Levodopa Inhalation Powder.

ABSTRACT: Oral levodopa is the most effective treatment for Parkinson disease, but OFF periods emerge over time. Gastrointestinal dysfunction and food effects impact levodopa absorption, contributing to unpredictable control of OFF periods. Inhaled levodopa powder (Inbrija) is approved for on-demand treatment of OFF periods in patients receiving oral levodopa-dopa decarboxylase inhibitors. The 84-mg dose is administered via a breath-actuated inhaler. It provides pulmonary delivery of levodopa to the systemic circulation and is taken when a patient has an OFF period in between doses of regular oral levodopa medication. The pivotal SPAN-PD trial in patients experiencing OFF periods on oral dopaminergic therapy showed that levodopa inhalation powder 84 mg produced significant improvement in Unified Parkinson Disease Rating Scale Part III score, as measured 30 minutes postdose at week 12, and improvement was seen as early as 10 minutes. More patients in the levodopa inhalation powder group turned ON within 60 minutes of treatment and remained ON at 60 minutes than in the placebo group. Levodopa inhalation powder can also be used to treat early-morning OFF periods and, when used for up to 12 months, produced no clinically significant differences in pulmonary function compared with an untreated cohort. Levodopa inhalation powder 84 mg increased plasma levodopa concentration rapidly and with less variability than oral levodopa/carbidopa (25/100 mg). Most common adverse event associated with levodopa inhalation powder is cough, found in ~15% of patients in the SPAN-PD trial; otherwise, reported adverse events were consistent with those known to be associated with oral levodopa.

Gene-based burden analysis of damaging private variants in PRKN, PARK7 and PINK1 in Parkinson's disease cohorts of European descent.

Recessive mutations in PRKN, PARK7, and PINK1 are established causes of early-onset Parkinson's disease (EOPD). Previous studies have interrogated the role of heterozygous variants in these genes but mainly focused on rare (minor allele frequency [MAF] <1%) damaging variants or established mutations. Here, we assessed heterozygous private PRKN, PARK7 and PINK1 variants in PD risk in four large-scale PD case-control datasets by performing gene-wise burden analyses using sequencing data totaling 5,829 PD cases and 7,221 controls, and summary allele counts from 9,501 PD cases and 48,207 controls. Results showed no significant burden in all three genes after meta-analyses. Burden in EOPD (age at onset <50 years) and late-onset PD (≥50 years) remained nonsignificant. In summary, we found no evidence to support the association of the excess burden of heterozygous private variants in PRKN, PARK7, and PINK1 with PD risk in the European population. Larger, more diverse cohorts are needed to accurately determine their role in PD.

A 12-month, dose-level blinded safety and efficacy study of levodopa inhalation powder (CVT-301, Inbrija) in patients with Parkinson's disease.

INTRODUCTION: CVT-301 (Inbrija®) is a levodopa inhalation powder for on-demand treatment of OFF episodes in Parkinson's disease patients treated with carbidopa/levodopa. Safety and efficacy results of a 12-month, dose-level blinded extension study of a phase 3 trial (SPAN℠-PD) of CVT-301 are presented. METHODS: Patients were receiving oral carbidopa/levodopa and adjunctive CVT-301 treatment, blinded to dose (60 mg or 84 mg, N = 325). Study visits occurred every 3 months. Pulmonary function was assessed by spirometry. Other safety assessments included dyskinesia and adverse events (AEs). Secondary objectives of the study included maintenance of improvement assessments for occurrence of an ON state during the 60-min post-dose period, change in total daily OFF time, and Patient Global Impression of Change (PGIC). RESULTS: Most frequent AEs (≥5%) were cough (15.4%), fall (13.1%), upper respiratory tract infection (7.1%), and dyskinesia (5.1%). Severe AEs (>1 event) were cough (1.9%) and dyskinesia (0.6%). Twelve-month mean changes from baseline for FEV1, FVC, and DLCO were -0.092 L, -0.097 L, and -0.922 mL/min/mmHg, respectively. At 12 months, 73.0% of patients on 84 mg achieved an ON state within 60 min. Total daily OFF time was reduced by 0.55 h (month 1) and 0.88 h (month 12) for the 84 mg dose. Percentage of patients self-reported as improved by PGIC was 65.5-91.9% over 12 months. CONCLUSION: CVT-301 was generally well-tolerated. Twelve-month decline in pulmonary function was consistent with a prior PD control group. Exploratory efficacy results showed CVT-301 maintained improvement at achieving ON states in patients experiencing OFF episodes, decreasing daily OFF time, and maintaining improvement in PGIC.

Analysis of common and rare VPS13C variants in late-onset Parkinson disease.

OBJECTIVE: We aimed to study the role of coding VPS13C variants in a large cohort of patients with late-onset Parkinson disease (PD) (LOPD). METHODS: VPS13C and its untranslated regions were sequenced using targeted next-generation sequencing in 1,567 patients with PD and 1,667 controls from 3 cohorts. Association tests of rare potential homozygous and compound heterozygous variants and burden tests for rare heterozygous variants were performed. Common variants were analyzed using logistic regression adjusted for age and sex in each of the cohorts, followed by a meta-analysis. RESULTS: No biallelic carriers of rare VPS13C variants were found among patients, and 2 carriers of compound heterozygous variants were found in 2 controls. There was no statistically significant burden of rare (minor allele frequency [MAF] <1%) or very rare (MAF <0.1%) coding VPS13C variants in PD. A VPS13C haplotype including the p.R153H-p.I398I-p.I1132V-p.Q2376Q variants was nominally associated with a reduced risk for PD (meta-analysis of the tagging SNP p.I1132V [odds ratio = 0.48, 95% confidence interval = 0.28-0.82, p = 0.0052]). This haplotype was not in linkage disequilibrium with the known genome-wide association study top hit. CONCLUSIONS: Our results do not support a role for rare heterozygous or biallelic VPS13C variants in LOPD. Additional genetic replication and functional studies are needed to examine the role of the haplotype identified here associated with reduced risk for PD.

Optimizing extended-release carbidopa/levodopa in Parkinson disease: Consensus on conversion from standard therapy.

PURPOSE OF REVIEW: To help clinicians optimize the conversion of a patient's Parkinson disease pharmacotherapy from immediate-release carbidopa/levodopa (IR CD/LD) to an extended-release formulation (ER CD/LD). RECENT FINDINGS: Eleven movement disorders specialists achieved consensus positions on the modification of trial-based conversion guidelines to suit individual patients in clinical practice. SUMMARY: Because the pharmacokinetics of ER CD/LD differ from those of IR CD/LD, modification of dosage and dosing frequency are to be expected. Initial regimens may be based on doubling the patient's preconversion levodopa daily dosage and choosing a division of doses to address the patient's motor complications, e.g., wearing-off (warranting a relatively high ER CD/LD dose, possibly at a lower frequency than for IR CD/LD) or dyskinesia (warranting a relatively low dose, perhaps at an unchanged frequency). Patients should know that the main goal of conversion is a steadier levodopa clinical response, even if dosing frequency is unchanged.

Elevated GM3 plasma concentration in idiopathic Parkinson's disease: A lipidomic analysis.

Parkinson's disease (PD) is a common neurodegenerative disease whose pathological hallmark is the accumulation of intracellular α-synuclein aggregates in Lewy bodies. Lipid metabolism dysregulation may play a significant role in PD pathogenesis; however, large plasma lipidomic studies in PD are lacking. In the current study, we analyzed the lipidomic profile of plasma obtained from 150 idiopathic PD patients and 100 controls, taken from the 'Spot' study at Columbia University Medical Center in New York. Our mass spectrometry based analytical panel consisted of 520 lipid species from 39 lipid subclasses including all major classes of glycerophospholipids, sphingolipids, glycerolipids and sterols. Each lipid species was analyzed using a logistic regression model. The plasma concentrations of two lipid subclasses, triglycerides and monosialodihexosylganglioside (GM3), were different between PD and control participants. GM3 ganglioside concentration had the most significant difference between PD and controls (1.531±0.037 pmol/µl versus 1.337±0.040 pmol/µl respectively; p-value = 5.96E-04; q-value = 0.048; when normalized to total lipid: p-value = 2.890E-05; q-value = 2.933E-03). Next, we used a collection of 20 GM3 and glucosylceramide (GlcCer) species concentrations normalized to total lipid to perform a ROC curve analysis, and found that these lipids compare favorably with biomarkers reported in previous studies (AUC = 0.742 for males, AUC = 0.644 for females). Our results suggest that higher plasma GM3 levels are associated with PD. GM3 lies in the same glycosphingolipid metabolic pathway as GlcCer, a substrate of the enzyme glucocerebrosidase, which has been associated with PD. These findings are consistent with previous reports implicating lower glucocerebrosidase activity with PD risk.

SCARB2 variants and glucocerebrosidase activity in Parkinson's disease.

Mutations in glucocerebrosidase (GBA) are a common risk factor for Parkinson's disease (PD). The scavenger receptor class B member 2 (SCARB2) gene encodes a receptor responsible for the transport of glucocerebrosidase (GCase) to the lysosome. Two common SNPs in linkage disequilibrium with SCARB2, rs6812193 and rs6825004, have been associated with PD and Lewy Body Disease in genome wide association studies. Whether these SNPs are associated with altered glucocerebrosidase enzymatic activity is unknown. Our objective was to determine whether SCARB2 SNPs are associated with PD and with reduced GCase activity. The GBA gene was fully sequenced, and the LRRK2 G2019S and SCARB2 rs6812193 and rs6825004 SNPs were genotyped in 548 PD patients and 272 controls. GCase activity in dried blood spots was measured by tandem mass spectrometry. We tested the association between SCARB2 genotypes and PD risk in regression models adjusted for gender, age, and LRRK2 G2019S and GBA mutation status. We compared GCase activity between participants with different genotypes at rs6812193 and rs6825004. Genotype at rs6812193 was associated with PD status. PD cases were less likely to carry the T allele than the C allele (OR=0.71; p=0.004), but GCase enzymatic activity was similar across rs6812193 genotypes (C/C: 11.88 µmol/l/h; C/T: 11.80 µmol/l/h; T/T: 12.02 µmol/l/h; p=0.867). Genotype at rs6825004 was not associated with either PD status or GCase activity. In conclusion, our results support an association between SCARB2 genotype at rs6812193 and PD, but suggest that the increased risk is not mediated by GCase activity.

Long-Term Treatment with Extended-Release Carbidopa-Levodopa (IPX066) in Early and Advanced Parkinson's Disease: A 9-Month Open-Label Extension Trial.

BACKGROUND AND OBJECTIVE: IPX066 is a multiparticulate extended-release formulation of carbidopa-levodopa, designed to produce prolonged therapeutic levodopa plasma concentrations. This 9-month open-label extension study assessed its long-term safety and clinical utility in early and advanced Parkinson's disease (PD). METHODS: Participants were enrolled from two phase III IPX066 studies and one open-label phase II study. Early PD patients were titrated to an appropriate dosing regimen while advanced patients started with regimens established in the antecedent studies. Adjustment was allowed throughout the extension. Clinical utility measures included the Unified Parkinson's Disease Rating Scale (UPDRS) and Patient Global Impression (PGI) ratings. RESULTS: Among 268 early PD patients, 53.4 % reported adverse events (AEs) and 1.1 % (three patients) discontinued due to AEs; the most frequent AEs were nausea (5.6 %) and insomnia (5.6 %). Among 349 advanced patients, 60.2 % reported AEs and 3.7 % (13 patients) discontinued due to AEs; the most frequent AEs were dyskinesia (6.9 %) and fall (6.6 %). At month 9 (or early termination), 78.3 % of early patients were taking IPX066 three times daily (median: 720 mg/day) and 87.7 % of advanced patients were taking IPX066 three or four times daily (median: 1450 mg/day). Adjusting for 70 % bioavailability relative to immediate-release (IR) carbidopa-levodopa, the median dosages correspond to ~500 and ~1015 mg/day of IR levodopa in early and advanced PD, respectively. Based on the plasma profiles previously observed in PD patients, the IPX066 regimens in the extension can be estimated to provide a levodopa Cmax (maximum plasma drug concentration) similar to or lower than that provided by IR regimens during the antecedent trials. UPDRS and PGI findings showed sustained treatment effects throughout the extension. CONCLUSION: During 9 months of extended use, IPX066 exhibited a safety/tolerability profile consistent with dopaminergic PD therapy.

Treatment of advanced stage patients with Parkinson's disease.

Most patients with Parkinson's disease (PD) receiving chronic levodopa therapy eventually manifest one or more motor response complications, including 'wearing-off' phenomena and on-off phenomena. Additionally, as the disease progresses, motor, neurologic, and neuropsychiatric complications increase and may include freezing spells, falls, dementia, depression and psychosis. The management of patients with advanced PD presents a special clinical challenge because patients may experience an enhanced sensitivity to small changes in plasma levodopa levels and because they may suffer adverse reactions to antiparkinsonian drugs. Management of advanced PD is directed toward decreasing the dose of the offending drug while raising the dose of alternative drug with the goal of maintaining symptom control. In this article, the spectrum of late complications experienced by patients with advanced PD and their management are discussed.

Cognitive and motor function in long-duration PARKIN-associated Parkinson disease.

IMPORTANCE: Data on the long-term cognitive outcomes of patients with PARKIN-associated Parkinson disease (PD) are unknown but may be useful when counseling these patients. OBJECTIVE: Among patients with early-onset PD of long duration, we assessed cognitive and motor performances, comparing homozygotes and compound heterozygotes who carry 2 PARKIN mutations with noncarriers. DESIGN, SETTING, AND PARTICIPANTS: Cross-sectional study of 44 participants at 17 different movement disorder centers who were in the Consortium on Risk for Early-Onset PD study with a duration of PD greater than the median duration (>14 years): 4 homozygotes and 17 compound heterozygotes (hereafter referred to as carriers) and 23 noncarriers. MAIN OUTCOMES AND MEASURES: Unified Parkinson Disease Rating Scale Part III (UPDRS-III) and Clinical Dementia Rating scores and neuropsychological performance. Linear regression models were applied to assess the association between PARKIN mutation status and cognitive domain scores and UPDRS-III scores. Models were adjusted for age, education, disease duration, language, and levodopa equivalent daily dose. RESULTS: Carriers had an earlier age at onset of PD (P < .001) and were younger (P = .004) at time of examination than noncarriers. They performed better than noncarriers on the Mini-Mental State Examination (P = .010) and were more likely to receive lower scores on the Clinical Dementia Rating (P = .003). In multivariate analyses, carriers performed better than noncarriers on the UPDRS-III (P = .02) and on tests of attention (P = .03), memory (P = .03), and visuospatial (P = .02) cognitive domains. CONCLUSIONS AND RELEVANCE: In cross-sectional analyses, carriers demonstrated better cognitive and motor performance than did noncarriers with long disease duration, suggesting slower disease progression. A longitudinal follow-up study is required to confirm these findings.

A randomized clinical trial of high-dosage coenzyme Q10 in early Parkinson disease: no evidence of benefit.

IMPORTANCE: Coenzyme Q10 (CoQ10), an antioxidant that supports mitochondrial function, has been shown in preclinical Parkinson disease (PD) models to reduce the loss of dopamine neurons, and was safe and well tolerated in early-phase human studies. A previous phase II study suggested possible clinical benefit. OBJECTIVE: To examine whether CoQ10 could slow disease progression in early PD. DESIGN, SETTING, AND PARTICIPANTS: A phase III randomized, placebo-controlled, double-blind clinical trial at 67 North American sites consisting of participants 30 years of age or older who received a diagnosis of PD within 5 years and who had the following inclusion criteria: the presence of a rest tremor, bradykinesia, and rigidity; a modified Hoehn and Yahr stage of 2.5 or less; and no anticipated need for dopaminergic therapy within 3 months. Exclusion criteria included the use of any PD medication within 60 days, the use of any symptomatic PD medication for more than 90 days, atypical or drug-induced parkinsonism, a Unified Parkinson's Disease Rating Scale (UPDRS) rest tremor score of 3 or greater for any limb, a Mini-Mental State Examination score of 25 or less, a history of stroke, the use of certain supplements, and substantial recent exposure to CoQ10. Of 696 participants screened, 78 were found to be ineligible, and 18 declined participation. INTERVENTIONS: The remaining 600 participants were randomly assigned to receive placebo, 1200 mg/d of CoQ10, or 2400 mg/d of CoQ10; all participants received 1200 IU/d of vitamin E. MAIN OUTCOMES AND MEASURES: Participants were observed for 16 months or until a disability requiring dopaminergic treatment. The prospectively defined primary outcome measure was the change in total UPDRS score (Parts I-III) from baseline to final visit. The study was powered to detect a 3-point difference between an active treatment and placebo. RESULTS: The baseline characteristics of the participants were well balanced, the mean age was 62.5 years, 66% of participants were male, and the mean baseline total UPDRS score was 22.7. A total of 267 participants required treatment (94 received placebo, 87 received 1200 mg/d of CoQ10, and 86 received 2400 mg/d of CoQ10), and 65 participants (29 who received placebo, 19 who received 1200 mg/d of CoQ10, and 17 who received 2400 mg/d of CoQ10) withdrew prematurely. Treatments were well tolerated with no safety concerns. The study was terminated after a prespecified futility criterion was reached. At study termination, both active treatment groups showed slight adverse trends relative to placebo. Adjusted mean changes (worsening) in total UPDRS scores from baseline to final visit were 6.9 points (placebo), 7.5 points (1200 mg/d of CoQ10; P = .49 relative to placebo), and 8.0 points (2400 mg/d of CoQ10; P = .21 relative to placebo). CONCLUSIONS AND RELEVANCE: Coenzyme Q10 was safe and well tolerated in this population, but showed no evidence of clinical benefit. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT00740714.

Continuous dopaminergic delivery to minimize motor complications in Parkinson's disease.

Motor fluctuations and dyskinesias are common sequelae of Parkinson's disease (PD) that may limit function and quality of life. With disease progression, striatal dopamine concentration becomes closely linked to plasma levodopa levels, which vary considerably with standard oral regimens. Exposure of striatal dopamine receptors to wildly fluctuating transmitter levels is thought to contribute to the development of dyskinesias and motor fluctuations. Continuous dopaminergic delivery has been shown to reduce motor complications in advanced PD patients, and has been hypothesized to prevent their incidence when given as early therapy in mild PD. In this article, the authors outline the rationale for continuous dopaminergic delivery and review clinical strategies implementing the concept, including transdermal rotigotine, subcutaneous apomorphine infusion, intraduodenal infusion of levodopa gel and the investigational oral levodopa formulation IPX066.

Self-report of cognitive impairment and mini-mental state examination performance in PRKN, LRRK2, and GBA carriers with early onset Parkinson's disease.

While little is known about risk factors for cognitive impairment in early onset Parkinson disease (EOPD), postmortem studies have shown an association between dementia with Lewy bodies (DLB) and glucocerebrosidase (GBA) mutation. We compared Mini-Mental State Examination (MMSE) performance and self-reported cognitive impairment in 699 EOPD participants genotyped for mutations in parkin (PRKN), leucine-rich repeat kinase-2 (LRRK2), and GBA. Logistic regression was used to assess the association between reported cognitive impairment and MMSE score, as well as between GBA group membership and self-reported impairment and MMSE. GBA carriers reported more impairment, but MMSE performance did not differ among genetic groups. Detailed neuropsychological testing is required to explore the association between cognitive impairment and GBA mutations.

Current strategies in the treatment of Parkinson's disease and a personalized approach to management.

Parkinson's disease is a progressive, neurodegenerative disorder affecting millions of people worldwide. Given the aging population, the prevalence of the disease is expected to increase substantially. The mainstay of treatment has been dopamine replacement therapy with carbidopa, levodopa, dopamine agonists, monoamine oxidase type B inhibitors, catechol-O-methyltransferase inhibitors and amantadine. Nonmotor features, such as cognitive impairment, mood disorders, autonomic dysfunction, gastrointestinal and genitourinary dysfunction, have a substantial impact on Parkinson's disease patients and their quality of life. This review will provide an overview on medications currently available for management of both motor and nonmotor symptoms of Parkinson's disease. Focus will be placed on recent and evolving studies evaluating symptomatic and neuroprotective effects of medications, and how such studies may impact the future management of Parkinson's disease.

Motor phenotype of LRRK2 G2019S carriers in early-onset Parkinson disease.

OBJECTIVE: To determine the motor phenotype of LRRK2 G2019S mutation carriers. LRRK2 mutation carriers were previously reported to manifest the tremor dominant motor phenotype, which has been associated with slower motor progression and less cognitive impairment compared with the postural instability and gait difficulty (PIGD) phenotype. DESIGN: Cross-sectional observational study. SETTING: Thirteen movement disorders centers. PARTICIPANTS: Nine hundred twenty-five early-onset Parkinson disease cases defined as age at onset younger than 51 years. MAIN OUTCOME MEASURES: LRRK2 mutation status and Parkinson disease motor phenotype: tremor dominant or PIGD. Demographic information, family history of Parkinson disease, and the Unified Parkinson's Disease Rating Scale score were collected on all participants. DNA samples were genotyped for LRRK2 mutations (G2019S, I2020T, R1441C, and Y1699C). Logistic regression was used to examine associations of G2019S mutation status with motor phenotype adjusting for disease duration, Ashkenazi Jewish ancestry, levodopa dose, and family history of Parkinson disease. RESULTS: Thirty-four cases (3.7%) (14 previously reported) were G2019S carriers. No other mutations were found. Carriers were more likely to be Ashkenazi Jewish (55.9% vs 11.9%; P < .001) but did not significantly differ in any other demographic or disease characteristics. Carriers had a lower tremor score (P = .03) and were more likely to have a PIGD phenotype (92.3% vs 58.9%; P = .003). The association of the G2019S mutation with PIGD phenotype remained after controlling for disease duration and Ashkenazi Jewish ancestry (odds ratio, 17.7; P < .001). CONCLUSION: Early-onset Parkinson disease G2019S LRRK2 carriers are more likely to manifest the PIGD phenotype, which may have implications for disease course.

Corticobasal Degeneration.

Corticobasal degeneration is one of the neurodegenerative tauopathies, which are defined as a group of heterogeneous dementias and movement disorders that are characterized neuropathologically by prominent intracellular accumulations of abnormal filaments formed by the microtubule-associated protein tau. Although there are no curative treatments, symptomatic and supportive management can be helpful. Many new therapies are still under development. However, more needs to be learned about the pathogenesis and molecular biology of this disease before an effective therapy can be developed.