Analysis of 14 LRRK2 mutations in Parkinson's plus syndromes and late-onset Parkinson's disease.

The pleomorphic pathology of postmortem LRRK2-positive patients and the frequent association with late-onset Parkinson's disease (LOPD) symptoms suggest that LRRK2 mutations may play a role in Parkinson's Plus disorders and LOPD. Published studies primarily focus on the common G2019S mutation. Analysis of a spectrum of LRRK2 mutations in Parkinson's Plus disorders has yet to be reported. We investigated 14 leucine-rich repeat kinase 2 (LRRK2) mutations in a cohort of Parkinson's Plus disorders and LOPD. A total of 458 patients with progressive supranuclear palsy (PSP), multiple system atrophy (MSA), corticobasal ganglionic degeneration (CBGD), atypical Parkinsonism (AP), and LOPD were screened for 14 mutations that span exons 19 to 41 of the LRRK2 gene. Among the LOPD cases, 1 patient was found to harbor the R1441C mutation. He presented with typical features of PD at age of 58 years old and responded well to levodopa. We did not detect any of the 14 mutations in PSP, MSA, CBGD, and AP patients. We highlight the first case of LRRK2 R1441C mutation in late onset sporadic PD of non-European ancestry. Furthermore, extensive mutational screen found LRRK2 mutations to be rare among patients who presented with PSP, MSA, CBGD, and AP.     

Mutations in LRRK2 other than G2019S are rare in a north american–based sample of familial Parkinson's disease

A total of 956 individuals with Parkinson's disease (PD) from 430 multiplex PD pedigrees were screened for 12 previously reported, pathogenic LRRK2 mutations: R793M, L1114L, I1371V, R1441C, R1441G, R1441H, Y1699C, M1869T, I2012T, I2020T, G2385R, and IVS31 +3G>A. Previous screening identified the LRRK2 G2019S mutation in 5% of our families. Only 1 of the 12 newly screened mutations, R1441C, was detected in a single family in our patient cohort. These results indicate that, although the G2019S mutation remains the most common mutation identified in familial PD patients, other mutations in LRRK2 are infrequent. © 2006 Movement Disorder Society     

Identification of blood serum micro‐RNAs associated with idiopathic and LRRK2 Parkinson's disease

Blood‐cell‐free circulating micro‐RNAs (miRNAs) have been proposed as potential accessible biomarkers for neurodegenerative diseases such as Parkinson's disease (PD). Here we analyzed the serum levels of 377 miRNAs in a discovery set of 10 idiopathic Parkinson's disease (IPD) patients, 10 PD patients carriers of the LRRK2 G2019S mutation (LRRK2 PD), and 10 controls by using real‐time quantitative PCR‐based TaqMan MicroRNA arrays. We detected candidate differentially expressed miRNAs, which were further tested in a first validation set consisting of 20 IPD, 20 LRRK2 PD, and 20 control samples. We found four statistically significant miRNAs that were downregulated in either LRRK2 or IPD (miR‐29a, miR‐29c, miR‐19a, and miR‐19b). Subsequently, we validated these findings in a third set of samples consisting of 65 IPD and 65 controls and confirmed the association of downregulated levels of miR‐29c, miR‐29a, and miR‐19b in IPD. Differentially expressed miRNAs are predicted to target genes belonging to pathways related to ECM–receptor interaction, focal adhesion, MAPK, Wnt, mTOR, adipocytokine, and neuron projection. Results from our exploratory study indicate that downregulated levels of specific circulating serum miRNAs are associated with PD and suggest their potential use as noninvasive biomarkers for PD. Future studies should further confirm the association of these miRNAs with PD. © 2014 Wiley Periodicals, Inc.     

G2019S LRRK2 mutation in familial and sporadic Parkinson's disease in Russia.

Among mutations associated with autosomal dominant and sporadic Parkinson's disease (PD) the G2019S substitution in the leucine-rich repeat kinase 2 (LRRK2) gene is the most frequently identified. To estimate its frequency in Russia, we analyzed 208 patients with PD from the Northwestern region of Russia. Of these, 51 patients were probands from families with PD compatible with autosomal dominant inheritance. The control group represented 161 subjects without neurological disorders settled in the same region. The frequency of the G2019S mutation was greater in familial PD (2 [3.9%] of 51) than in sporadic PD (1 [0.6%] of 157). In addition, this mutation was found in the proband's father, who also had PD, in 1 PD family, and in 1 carrier without signs of PD at age 40 in another PD family. All carriers were heterozygous for the G2019S mutation and reported the Ashkenazi Jewish origin. The mutation was not found in the control group.     

R1514Q substitution in Lrrk2 is not a pathogenic Parkinson's disease mutation.

Mutations in LRRK2 were first reported as causing Parkinson's disease (PD) in late 2004. Since then, approximately a dozen LRRK2 substitutions have been identified that are believed to be pathogenic mutations. The substitution of adenine for guanine at nucleotide 4541 (4541G>A) in LRRK2 was recently reported. This substitution resulted in the replacement of an arginine at position 1514 with a glutamine (R1514Q). Although this substitution was not found in a large cohort of controls, its pathogenicity could not be verified. We have now genotyped the R1514Q substitution in a sample of 954 PD patients from 429 multiplex PD families. This substitution was identified in 1.8% of the PD patients; however, the majority of the PD sibships segregating this substitution were discordant for this putative mutation. In addition, the R1514Q substitution was detected in 1.4% of neurologically evaluated, control individuals. These data suggest that the R1514Q variant is not a pathogenic LRRK2 mutation. We believe it is imperative that the causative nature of any newly identified genetic variant be determined before it is included in any panel for diagnostic testing.     

Lack of G2019S LRRK2 mutation in a cohort of Taiwanese with sporadic Parkinson's disease.

Mutations in the leucine-rich repeat kinase 2 (LRRK2) gene have been shown to cause autosomal dominant and sporadic Parkinson's disease (PD). We report here the frequency of a common heterozygous mutation, 2877510G>A, which produces a glycine-to-serine amino acid substitution at codon 2019 in idiopathic Taiwanese PD. The extreme rarity of the G2019S mutation in our population suggests the occurrence of this mutation resulted from a common European founder.     

Induced pluripotent stem cell‐based modeling of mutant LRRK2‐associated Parkinson's disease

Recent advances in cell reprogramming have enabled assessment of disease‐related cellular traits in patient‐derived somatic cells, thus providing a versatile platform for disease modeling and drug development. Given the limited access to vital human brain cells, this technology is especially relevant for neurodegenerative disorders such as Parkinson's disease (PD) as a tool to decipher underlying pathomechanisms. Importantly, recent progress in genome‐editing technologies has provided an ability to analyze isogenic induced pluripotent stem cell (iPSC) pairs that differ only in a single genetic change, thus allowing a thorough assessment of the molecular and cellular phenotypes that result from monogenetic risk factors. In this review, we summarize the current state of iPSC‐based modeling of PD with a focus on leucine‐rich repeat kinase 2 (LRRK2), one of the most prominent monogenetic risk factors for PD linked to both familial and idiopathic forms. The LRRK2 protein is a primarily cytosolic multi‐domain protein contributing to regulation of several pathways including autophagy, mitochondrial function, vesicle transport, nuclear architecture and cell morphology. We summarize iPSC‐based studies that contributed to improving our understanding of the function of LRRK2 and its variants in the context of PD etiopathology. These data, along with results obtained in our own studies, underscore the multifaceted role of LRRK2 in regulating cellular homeostasis on several levels, including proteostasis, mitochondrial dynamics and regulation of the cytoskeleton. Finally, we expound advantages and limitations of reprogramming technologies for disease modeling and drug development and provide an outlook on future challenges and expectations offered by this exciting technology.     

Pathogenicity of LRRK2 P755L variant in Parkinson's disease

A heterozygous 2264C→T variant (P755L) in LRRK2 gene has been reported to be a likely pathogenic variant among ethnic Chinese patients with Parkinson's disease (PD). In a case control study, we performed genetic analysis of the P755L variant in an independent cohort of Chinese patients with PD and controls. The P755L variant was present in 4/204 (2.0%) of PD compared with 6/235 (2.6%) of controls (odds ratio = 0.76, 95% CI 0.23, 2.6, P = 0.76). All subjects carried the heterozygous genotype. Subset analysis in the group ≥65 years of age revealed a prevalence of 2.8% in PD compared with 3.1% in controls (odds ratio = 0.92, 95% CI 022, 3.7, P = 0.9), and in the group <65 years of age showed a 0% in PD versus 2.1% in controls (P = 0.2). The phenotype of patients with PD with the P755L variant was generally similar to other patients with PD and none of the carriers reported a positive family history. The lack of functional data, absence of segregation of the variant with disease, and the presence of the variant in apparently healthy individuals suggest that P755L is possibly a rare polymorphism in the Chinese population. Further validation of our findings in other populations would be important. © 2008 Movement Disorder Society     

High prevalence of LRRK2 mutations in familial and sporadic Parkinson's disease in Portugal.

Mutations in the Leucine-Rich Repeat Kinase 2 (LRRK2) gene are the most frequent known cause of Parkinson's disease (PD), but their prevalence varies markedly between populations. Here we studied the frequency and associated phenotype of four recurrent LRRK2 mutations (R1441C, R1441G, R1441H, and G2019S) in familial and sporadic PD from a single referral center in Lisbon, Portugal. Among 138 unrelated PD probands, we identified 9 heterozygous G2019S carriers (6.52%) and 1 heterozygous R1441H carrier (0.72%). The G2019S mutation was present in 4 of the 107 sporadic (3.74%) and in 5 of the 31 familial probands (16.1%). Mutations were not found among 101 Portuguese controls. The G2019S mutation was present on a single haplotype and displayed reduced penetrance. Heterozygous parkin gene mutations were also found in 2 G2019S-positive probands, but their pathogenic role is unclear. The clinical phenotype in patients with LRRK2 mutations was indistinguishable from that of typical PD, including impaired sense of smell. The G2019S mutation is a very common genetic determinant among the Portuguese patients with PD, and the R1441H mutation is also present in this population. These data have important implications for the diagnostic work-up and genetic counseling of patients with this disease in Portugal.     

A novel LRRK2 mutation in an Austrian cohort of patients with Parkinson's disease.

To investigate the frequency of mutations in the Leucine-Rich Repeat Kinase 2 gene (LRRK2) in a sample of Austrian Parkinson's disease (PD) patients, we sequenced the complete coding region in 16 patients with autosomal dominant PD. Furthermore, we sequenced exons 31, 35, and 41 additionally in 146 patients with idiopathic PD and 30 patients with dementia with Lewy bodies. Furthermore, all 192 patients were screened for 21 putative LRRK2 mutations. While the most common mutation G2019S and the risk variant G2385R were not found in our samples, we detected a novel missense mutation (S973N) in a patient with familial, late-onset and dopa-responsive PD.     

Neuropathology of Parkinson's disease associated with the LRRK2 Ile1371Val mutation.

Leucine-Rich Repeat Kinase 2 (LRRK2) gene mutations are the most common known cause of Parkinson's disease (PD), but neuropathological studies are available on very few patients with LRRK2 mutation. The reported findings range from Lewy body-positive pathology to different pathologies, including nigral degeneration without distinctive features, neuronal loss with only ubiquitin-positive inclusions, and tau-positive-only pathology. Here we report the first neuropathological study in an Italian PD case carrying a different LRRK2 mutation, Ile1371Val, and showing typical ubiquitin- and alpha-synuclein-positive Lewy body pathology. These findings support the concept that the neurodegeneration associated with LRRK2 mutations might be clinically and pathologically indistinguishable from typical PD.     

Frequency and phenotypes of LRRK2 G2019S mutation in Italian patients with Parkinson's disease.

To evaluate the frequency of the LRRK2 G2019S mutation in Italy, we tested 1,072 probands with Parkinson's disease (PD; 822 sporadic and 250 familial): 20 patients (1.9%) carried the G2019S mutation, 11 patients (1.3%) were sporadic, and 9 (4.3%) had a positive family history. Considering only probands with autosomal dominant inheritance, the G2019S frequency raises to 5.2%. All presented a typical phenotype with variable onset and shared the common ancestral haplotype. Mutation frequency raised from 1.2% in early onset PD to 4.0% in late onset PD.     

Low‐fat versus ketogenic diet in Parkinson's disease: A pilot randomized controlled trial

Background : Preliminary evidence suggests that diet manipulation may influence motor and nonmotor symptoms in PD, but conflict exists regarding the ideal fat to carbohydrate ratio. Objectives : We designed a pilot randomized, controlled trial to compare the plausibility, safety, and efficacy of a low‐fat, high‐carbohydrate diet versus a ketogenic diet in a hospital clinic of PD patients. Methods : We developed a protocol to support PD patients in a diet study and randomly assigned patients to a low‐fat or ketogenic diet. Primary outcomes were within‐ and between‐group changes in MDS‐UPDRS Parts 1 to 4 over 8 weeks. Results : We randomized 47 patients, of which 44 commenced the diets and 38 completed the study (86% completion rate for patients commencing the diets). The ketogenic diet group maintained physiological ketosis. Both groups significantly decreased their MDS‐UPDRS scores, but the ketogenic group decreased more in Part 1 (?4.58 ± 2.17 points, representing a 41% improvement in baseline Part 1 scores) compared to the low‐fat group (?0.99 ± 3.63 points, representing an 11% improvement) (P < 0.001), with the largest between‐group decreases observed for urinary problems, pain and other sensations, fatigue, daytime sleepiness, and cognitive impairment. There were no between‐group differences in the magnitude of decrease for Parts 2 to 4. The most common adverse effects were excessive hunger in the low‐fat group and intermittent exacerbation of the PD tremor and/or rigidity in the ketogenic group. Conclusions : It is plausible and safe for PD patients to maintain a low‐fat or ketogenic diet for 8 weeks. Both diet groups significantly improved in motor and nonmotor symptoms; however, the ketogenic group showed greater improvements in nonmotor symptoms. © 2018 The Authors. Movement Disorders published by Wiley Periodicals, Inc. on behalf of International Parkinson and Movement Disorder Society.     

LRRK2 expression in idiopathic and G2019S positive Parkinson's disease subjects: a morphological and quantitative study

S. Sharma, R. Bandopadhyay, T. Lashley, A. E. M. Renton, A. E. Kingsbury, R. Kumaran, C. Kallis, C. Vilariño‐Güell, S. S. O'Sullivan, A. J. Lees, T. Revesz, N. W. Wood and J. L. Holton (2011) Neuropathology and Applied Neurobiology 37, 777–790 LRRK2 expression in idiopathic and G2019S positive Parkinson's disease subjects: a morphological and quantitative study Aims: Mutations in the gene encoding leucine‐rich repeat kinase‐2 (LRRK2) have been established as a common genetic cause of Parkinson's disease (PD). The distribution of LRRK2 mRNA and protein in the human brain has previously been described, although it has not been reported in PD cases with the common LRRK2 G2019S mutation. Methods: To further elucidate the role of LRRK2 in PD, we determined the localization of LRRK2 mRNA and protein in post‐mortem brain tissue from control, idiopathic PD (IPD) and G2019S positive PD cases. Results: Widespread neuronal expression of LRRK2 mRNA and protein was recorded and no difference was observed in the morphological localization of LRRK2 mRNA or protein between control, IPD and G2019S positive PD cases. Using quantitative real‐time polymerase chain reaction, we demonstrated that there is no regional variation in LRRK2 mRNA in normal human brain, but we have identified differential expression of LRRK2 mRNA with significant reductions recorded in limbic and neocortical regions of IPD cases compared with controls. Semi‐quantitative analysis of LRRK2 immunohistochemical staining demonstrated regional variation in staining intensity, with weak LRRK2 immunoreactivity consistently recorded in the striatum and substantia nigra. No clear differences were identified in LRRK2 immunoreactivity between control, IPD and G2019S positive PD cases. LRRK2 protein was identified in a small proportion of Lewy bodies. Conclusions: Our data suggest that widespread dysregulation of LRRK2 mRNA expression may contribute to the pathogenesis of IPD.