The LRRK2 G2019S mutation status does not affect the outcome of subthalamic stimulation in patients with Parkinson's disease

BackgroundDeep brain stimulation (DBS) of the subthalamic nucleus (STN) is an established therapy for advanced Parkinson's disease (PD). The most common genetic mutation associated with PD identified to date is the G2019S mutation of the LRRK2 gene, which is highly prevalent in the Ashkenazi Jewish population. The effect of STN-DBS surgery in patients carrying this mutation has not been systematically studied. We therefore performed a case-control study to evaluate the impact of the G2019S mutation status on the outcomes of bilateral STN-DBS.MethodsThe study sample included 39 Jewish PD patients with bilateral STN-DBS. Thirteen patients (5 females) were G2019S mutation heterozygous. The control group consisted of 26 PD patients with bilateral STN-DBS, negative for the mutation, matched (2:1) for gender, age at PD onset, and disease duration at surgery. Clinical data including the Unified PD Rating Scale scores (UPDRS), levodopa equivalent daily dose (LEDD), and clinical global impression of change (CGIC) concerning both motor and neuropsychiatric outcome- were available at 3 time points (preoperative baseline, 6–12 months and 3 years postoperatively).ResultsImplementing a linear mixed model, a significant improvement (p < 0.05) was found for the whole group concerning reduction in motor UPRDS (off state) and LEDD pre- vs. postoperatively, as expected. No difference in clinical outcome was found between carriers and matched non-carriers at baseline or at postoperative follow-up (up to 3 years).ConclusionsIn our study, STN-DBS outcomes were not influenced by the LRRK2 G2019S mutation, and thus knowledge of carrier status may not be relevant to the considerations of patient selection for surgery.     

LRRK2 mutations in Parkinson's disease: Confirmation of a gender effect in the Italian population

BackgroundThe relative risk of developing idiopathic PD is 1.5 times greater in men than in women, but an increased female prevalence in LRRK2-carriers has been described in the Ashkenazi Jewish population. We report an update about the frequency of major LRRK2 mutations in a large series of consecutive patients with Parkinson's disease (PD), including extensive characterization of clinical features. In particular, we investigated gender-related differences in motor and non-motor symptoms in the LRRK2 population.Methods2976 unrelated consecutive Italian patients with degenerative Parkinsonism were screened for mutations on exon 41 (G2019S, I2020T) and a subgroup of 1190 patients for mutations on exon 31 (R1441C/G/H). Demographic and clinical features were compared between LRRK2-carriers and non-carriers, and between male and female LRRK2 mutation carriers.ResultsLRRK2 mutations were identified in 40 of 2523 PD patients (1.6%) and not in other primary parkinsonian syndromes. No major clinical differences were found between LRRK2-carriers and non-carriers. We found a novel I2020L missense variant, predicted to be pathogenic. Female gender was more common amongst carriers than non-carriers (57% vs. 40%; p = 0.01), without any gender-related difference in clinical features. Family history of PD was more common in women in the whole PD group, regardless of their LRRK2 status.ConclusionsPD patients with LRRK2 mutations are more likely to be women, suggesting a stronger genetic load compared to idiopathic PD. Further studies are needed to elucidate whether there is a different effect of gender on the balance between genetic and environmental factors in the pathogenesis of PD.     

Autonomic dysfunction in parkinsonian LRRK2 mutation carriers

IntroductionThe aim of this study was to compare autonomic function in PD symptomatic carriers of the LRRK2 mutations and idiopathic Parkinson's disease (iPD) patients.Material and methodsWe studied 25 PD patients: 12 with the LRRK2 mutation (6 G2019S and 6 R1441G), and 13 with iPD. All patients underwent blood pressure and heart rate monitoring during head up tilt, Valsalva maneuver and deep breathing, along with recording of sympathetic skin response (SSR) and cardiac MIBG scintigraphy.ResultsThree of the patients with iPD and one of the LRRK2 carriers had orthostatic hypotension. Arterial pressure “overshoot” during phase IV of Valsalva maneuver was less pronounced in patients with iPD. During passive tilt, LRRK2 carries had higher increase of blood pressure than iPD patients MIBG late myocardial/mediastinal uptake ratios were higher in LRRK2 mutation carriers (1.51 ± 0.28 vs 1.32 ± 0.25; p < 0.05).DiscussionCarriers of the LRRK2 mutation had less autonomic impairment than those with iPD as shown by higher cardiac MIBG uptake and a tendency to less impairment of autonomic non-invasive tests. It is important to carry out larger studies comparing the clinical, functional and pathological characteristics of these patients.     

LRRK2 G2019S mutations are associated with an increased cancer risk in Parkinson disease

Leucine rich repeat kinase (LRRK2) G2019S mutations are presumed to cause PD through a toxic gain of function of the protein kinase. Small molecule kinase inhibitors have been developed for the treatment of certain cancers, and some antioncogenic agents such as sunitinib, may nonspecifically inhibit LRRK2. Few studies, however, have assessed cancer risk in LRRK2 mutation carriers. To explore this risk, we evaluated records of Ashkenazi Jewish (AJ) PD patients participating in genetic research. Charts were reviewed for 163 unrelated AJ PD patients, 31 of whom harbored the G2019S mutation. History of cancer was queried at baseline intake using a form reviewing medical conditions, and charts were reviewed for all follow‐up visits. 9/31 LRRK2 G2019S mutation carriers had nonskin cancers, whereas 15/132 without mutations had nonskin cancers, representing an almost threefold increased risk in this group (HR 2.9, 95% CI 1.3–6.6). Age at first nonskin cancer was younger in the LRRK2 carriers (56.0 years) than the noncarriers (62.0 years), but was not significant. 67% of the LRRK2 carriers had their cancer before the onset of PD, whereas only 40% of noncarriers developed their first nonskin cancer before onset of PD. While further evaluation is warranted, our findings indicate an increased risk of nonskin cancers in LRRK2 G2019S mutation carriers, which may be related to toxic gain of function of mutated LRRK2. © 2010 Movement Disorder Society     

Cognitive dysfunction in Tunisian LRRK2 associated Parkinson's disease

BackgroundCognitive impairment and dementia are frequent and debilitating features associated with idiopathic Parkinson’s disease (PD). However the prevalence and the pattern of these complications are lacking for LRRK2 (leucine-rich kinase 2)-associated PD patients.PurposeThe purpose of this study was to assess cognitive function in LRRK2- associated PD patients.Material and methods55 patients diagnosed with PD-related LRRK2 G2019S mutation were included in the study and compared to the same number of G2019S non-carriers PD patients. Age, sex, disease duration, the movement disorder society-unified Parkinson’s Disease rating scale (MDS-UPDRS), Hoehn and Yahr stage, Schwab and England scale and the 30-item geriatric depression scale (GDS) scores were noted. Cognitive assessment included MMSE (Mini-Mental Examination), MOCA (Montreal Cognitive Assessment) and FAB (Frontal Assessment Battery).ResultsMMSE, MOCA and FAB performance in G2019S carriers PD patients was similar to that of non-carriers. In both groups, performance was primarily impaired on visuospatial and executive tasks. Cognitive impairment was associated with older age, lower educational level and increased severity of motor impairment.ConclusionCognitive functions were similarly affected in PD patients with and without LRRK2 G2019S mutation with mainly impaired visuospatial and executive abilities. However, these results need to be confirmed by further large and prospective studies.     

LRRK2 and GBA mutations differentially affect the initial presentation of Parkinson disease

GBA and LRRK2 mutations increase susceptibility to Parkinson disease (PD), which is characterized by various disabling symptoms. An extended cohort of 600 Ashkenazi PD patients was screened for the LRRK2 G2019S and for eight GBA mutations. Reported initial symptoms were compared between three genotypic groups of patients: carriers of GBA mutations, carriers of LRRK2 G2019S mutation, and non-carriers. More LRRK2 G2019S carriers reported muscle stiffness (rigidity, p = 0.007) and balance disturbances (p = 0.008), while more GBA mutation carriers reported slowness (bradykinesia, p = 0.021). These results suggest distinct effects of LRRK2 or GBA mutations on the initial symptoms of PD.     

Prevalence and clinical features of common LRRK2 mutations in Australians with Parkinson's disease.

We determined the prevalence of two common leucine-rich repeat kinase 2 (LRRK2) gene mutations in Australian patients with Parkinson's disease (PD). Of 830 affected patients, eight were heterozygous for the G2019S mutation, and two were heterozygous for the R1441H (4,322 G > A) mutation. In addition, one familial patient had a novel A1442P (4,324 G > C) mutation. Haplotype analysis showed that all LRRK2 G2019S-positive individuals carried the common founder haplotype 1 and a putative founder haplotype for the R1441H mutation carriers. Clinically, patients with LRRK2 mutations had typical levodopa responsive Parkinsonism with tremor being the commonest presenting feature. Patients with the G2019S mutation in our series had a similar age of onset of symptoms when compared with patients with other LRRK2 mutations or sporadic PD, although they were more likely to have a family history of PD (2.4% of Australian patients with familial PD and 0.3% of Australian patients with sporadic PD). Our results demonstrate that the G2019S mutation carriers share the same ancestors who migrated to Australia originally from Europe and that other LRRK2 mutations (R1441H and A1442P) can be found in this population.     

Genealogical studies in LRRK2-associated Parkinson’s disease in central Norway

The most common mutation related to Parkinson’s disease (PD) is the p.G2019S mutation in the LRRK2 gene. Global population frequencies and crude estimates of haplotype conservation suggest most carriers are related. A total of 671 Norwegian PD patients and 215 of their family members were screened for the LRRK2 p.G2019S mutation. Twenty-one PD cases and 44 family members were positive for the mutation and all could be traced back to 10 different families. A genealogical study employed data from the Norwegian National Family Record Centre, local parish registers and population censuses. A common ancestor couple (living between 1580 and 1650) was found in six families, and two other families were associated by intermarriage. The remaining two families could not be traced back to either of these ancestors, though chromosome 12q12 haplotype analysis showed p.G2019S carriers shared alleles for 15 markers in the LRRK2 region.The study provides support for a common ancestor in Norwegian families with LRRK2 p.G2019S parkinsonism. The mutation was probably introduced to Norway through tradesmen from Europe. The extended pedigree that now links modern day carriers may help in mapping penetrance modifiers.     

Mutations in the Parkinson's disease genes,Leucine Rich Repeat Kinase 2 (LRRK2) and Glucocerebrosidase (GBA), are not associated with essential tremor

We evaluated an association between essential tremor (ET) and the Parkinson's disease (PD) genes, Leucine Rich Repeat Kinase 2 (LRRK2) and Glucocerebrosidase (GBA). Clinical studies demonstrate an association between ET and PD, suggesting possible shared pathophysiologies, yet LRRK2 has rarely been studied in ET, and GBA, not at all. ET cases (n = 275, including 42 with rest tremor) and controls (n = 289) were enrolled in an epidemiological study (Columbia University). Post-mortem brain tissue samples were obtained on 24 additional ET cases, including 3 with brainstem Lewy bodies. We performed a comprehensive analysis of the LRRK2 gene by genotyping 4 LRRK2 mutations (G2019S, I2020T, R1441C and Y1699C), 2 rare LRRK2 variants (L1114L and I1122V) and 19 LRRK2 SNPs. All GBA exons were sequenced in a subset of 93 Ashkenazi Jewish (AJ) cases, 62 AJ controls and 24 ET brains. LRRK2 mutations were not found in any ET cases or ET brains and none of the LRRK2 SNPs was associated with ET. GBA mutations were found in 7.5% (7/93) of AJ ET cases and 4.8% (3/62) of AJ controls (p = 0.75). 8.3% (2/24) of ET brains carried a GBA mutation. Four different heterozygous mutations were identified, including 3 previously reported mutations (N370S, R496H, and E326K) and 1 new missense variant (R44C). As suggested by several smaller prior reports, the known mutations for the LRRK2 gene are not risk factors for ET. Furthermore, a similar frequency of GBA mutations in AJ ET cases and controls suggests that GBA is not a common cause of ET either.     

A clinical, neuropsychological and olfactory evaluation of a large family with LRRK2 mutations

We evaluated the neurological and neuropsychological profiles and olfaction as presymptomatic markers in a large family with Parkinson disease (PD) caused by the G2019S mutation in the LRRK2 gene. Five affected family members, 14 asymptomatic mutation carriers and 15 non-carriers were compared. Patients had typical dopa-responsive PD, frequently associated with cognitive impairment. Asymptomatic carriers and non-carriers could not be distinguished because of their neuropsychological status, the presence of depression or olfactory impairment. We were therefore unable to identify a presymptomatic marker of LRRK2-related PD.     

The Age at Motor Symptoms Onset in <Emphasis Type="Italic">LRRK2</Emphasis>-Associated Parkinson's Disease is Affected by a Variation in the <Emphasis Type="Italic">MAPT</Emphasis> Locus: A Possible Interaction

The current paradigm on Parkinson's disease (PD) pathogenesis and course suggests the involvement of multiple genes and the interaction between them. Recently, it was reported that a variation (rs2435207) in the MAPT gene region influenced the age of motor symptoms onset (AO) in 44 PD patients from 19 families, carriers of leucine-rich repeat kinase 2 (LRRK2) mutations, all of European and North American origin. To examine whether genetic factors within the MAPT locus exert a similar effect on AO in a different population of LRRK2-associated PD patients, 99 unrelated Ashkenazi patients with the LRRK2 p.G2019S mutation were analyzed. Three SNPs in the MAPT region were studied, rs393152, rs2435207, and rs11079727; the latter is located in the first intron of MAPT. Among carriers of the single LRRK2 p.G2019S mutation that did not carry a founder Ashkenazi GBA mutation too (n = 84), the AO in minor rs11079727 A allele carriers (C/A genotype) was significantly older (62.5 ± 10.6 years) compared to the AO (55.7 ± 11.6) among carriers of the C/C genotype (p = 0.025). Our results further support a possible interaction between genetic factors in the MAPT region and the LRRK2 gene, which influence the clinical course of PD patients.     

Fall risk and gait in Parkinson's disease: The role of the LRRK2 G2019S mutation

Patients with Parkinson's disease (PD) who carry the G2019S mutation (a glycine to serine substitution at amino acid 2019) in the leucine‐rich repeat kinase 2 (LRRK2) gene are generally believed to be clinically indistinguishable from patients with sporadic PD. There are, however, conflicting reports on the relationship between the mutation and the motor phenotype. We quantitatively compared gait and mobility in patients with PD carriers of the G2019S mutation to non‐carrier patients with PD to better understand the genotype‐phenotype relationship. Fifty patients with PD carriers of the G2019S LRRK2 mutation and 50 age, disease duration, and disease severity matched PD non‐carriers were studied. An accelerometer quantified gait under three walking conditions: usual‐walking, dual‐tasking, and fast‐walking. The Unified Parkinson's Disease Rating Scale classified patients into PD sub‐types and the Timed Up and Go quantified mobility and fall risk. In all three walking conditions, gait variability was larger and the walking pattern was less consistent among the PD mutation carriers (P < 0.016). The PD carriers also took longer to complete the Timed Up and Go (P = 0.011) and were more likely to report having fallen in the previous year (P = 0.018). 64% of the PD carriers were classified as belonging to the postural‐instability‐gait‐difficulty (PIGD) sub‐type compared to only 17% of the PD non‐carriers (P < 0.0001). Among patients with PD, the G2019S mutation in the LRRK2 gene is apparently associated with increased gait variability, an increased fall risk, and the PIGD sub‐type. Therapeutic approach specifically designed to delay gait disturbances and falls may be justified in patients who carry the G2019S mutation. © 2013 International Parkinson and Movement Disorder Society     

Ashkenazi Parkinson’s disease patients with the LRRK2 G2019S mutation share a common founder dating from the second to fifth centuries

The LRRK2 G2019S mutation is a major genetic determinant of Parkinson’s disease (PD) across the world that occurs at an elevated frequency in Ashkenazi Jews. We determined the LRRK2 haplotypes in 77 G2019S carriers, mostly Ashkenazi Jews, and in 50 noncarrier Ashkenazi PD patients, using 16 genetic markers. A single haplotype was detected in all mutation carriers, indicating that these individuals share a common founder. Using a maximum-likelihood method, we estimate that Ashkenazi Jews with G2019S share a common ancestor who lived ～1,830 (95% CI 1,560–2,160) years ago, around the second century, after the second Jewish Diaspora.     

Prevalence of cancer in Parkinson's disease related to R1441G and G2019S mutations in LRRK2

An inverse relationship between Parkinson's disease (PD) and cancer has been described. However, the association between cancers and genetic forms of PD, in particular the R1441G mutation in the LRRK2 gene, is not well known. The objective of this work was to analyze cancer prevalence in PD patients with R1441G or G2019S mutations in LRRK2, and in idiopathic PD (iPD). A total of 732 patients with PD (70 and 25 carriers of R1441G or G2019S mutations, respectively), and 177 controls, were linked using a population‐based cancer registry of the Spanish province of Gipuzkoa. Cancer prevalence was not significantly higher in PD‐G2019S carriers (20%) than in PD‐R1441G carriers (14.3%), iPD (13.8%), or controls (12.5%). With the exception of a high prevalence of hematological cancers (crude odds ratio of 7.1) in the R1441G group, specific cancer types were not increased in PD mutation carriers. In both the carrier and iPD groups, cancers were diagnosed after the onset of PD. PD patients had a similar prevalence of cancer to control subjects. There was no increased association between G2019S or R1441G mutations and any type of cancer. Although there was a higher prevalence of hematological cancers in the R1441G group, the low number of such cancers overall makes this finding of uncertain significance. There was a slightly higher but not statistically significant prevalence of non‐skin cancers in the G2019S group, suggesting that further study to evaluate the association should be undertaken prior to ascribing an increased cancer risk to this population. © 2013 International Parkinson and Movement Disorder Society     

The LRRK2 G2385R variant is a risk factor for sporadic Parkinson's disease in the Korean population

The G2385R (SNP accession no. rs34778348) and R1628P (rs33949390) variants of leucine-rich repeat kinase 2 (LRRK2, PARK8) are emerging as an important risk factor for Parkinson's disease (PD) in the ethnic Chinese and Japanese populations. The purpose of this study was to investigate whether these variants are a genetic risk factor in sporadic PD patients in the Korean population. A total of 923 patients and 422 healthy subjects were included. The variants were screened by a SNaPshot assay. The LRRK2 G2385R variant was detected in 82 PD patients (8.9%, two homozygous and 80 heterozygous) and in 21 normal controls (5.0%, all heterozygous). The frequency of the LRRK2 G2385R variant in PD was significantly higher than in normal controls (adjusted odds ratio 1.83, p = 0.0170, 95% confidence interval 1.11–3.00). There were no differences in the mean age at onset or gender between the G2385R carriers and the non-carriers in PD patients. The LRRK2 R1628P variant was very rare (0.78% in patients versus 0.26% in controls) in the tested 384 patient–control pairs, and was not a significant risk factor. This study supports that the LRRK2 G2385R variant may be a genetic risk factor for sporadic PD in the Korean population.     

A common leucine-rich repeat kinase 2 gene mutation in familial and sporadic Parkinson's disease in Russia

A PARK8 form of Parkinson's disease (PD) is caused by a novel gene, leucine-rich repeat kinase 2 ( LRRK2 ), and a single mutation G2019S was found in a proportion of LRRK2 -associated cases of diverse ethnic origins. We performed the LRRK2 G2019S mutation analysis in 304 Russian patients with PD, including 291 sporadic and 13 autosomal dominant cases. The frequency of the LRRK2 G2019S was 0.7% amongst the sporadic patients (2/291) and 7.7% amongst familial PD (1/13). The mutation was also found in three unaffected relatives and absent in 700 control chromosomes. One patient carrying the LRRK2 G2019S was found earlier to have an additional mutation, a heterozygous duplication of exon 5 of the parkin gene. All patients carrying the LRRK2 G2019S exhibited typical levodopa-responsive parkinsonism, and severe levodopa-induced dyskinesia was observed in the patient carrying the LRRK2 and parkin mutations. There was notable variability in ages of the disease onset in G2019S carriers not explained by APOE genotypes. Two subsets of G2019S-positive patients had different PARK8 haplotypes suggesting that the LRRK2 G2019S in Russian patients had arisen independently on different chromosomes. Identification of common LRRK2 mutations in some PD patients without an overt family history has notable implications for genetic counseling.     

LRRK2 exon 41 mutations in sporadic Parkinson disease in Europeans

BACKGROUND: Mutations in leucine-rich repeat kinase 2 gene (LRRK2), particularly the G2019S mutation in exon 41, have been detected in familial and sporadic Parkinson disease (PD) cases. OBJECTIVES: To assess the frequency of LRRK2 exon 41 mutations in a series of sporadic PD cases from Europe and to determine the clinical features of LRRK2 mutation carriers. DESIGN: We analyzed European cases of sporadic PD for the presence of LRRK2 exon 41 mutations. These mutations were screened by denaturing high-performance liquid chromatography, and abnormal chromatograph traces were investigated by direct sequencing to determine the exact nature of the variants. Early-onset sporadic PD cases were also screened for parkin mutations. The haplotypes associated with the G2019S mutation were determined. The clinical characteristics of patients carrying LRRK2 mutations were detailed. SETTING: French Network for the Study of Parkinson Disease Genetics. Patients Three hundred twenty patients with apparently sporadic PD from Europe. MAIN OUTCOME MEASURES: Results of genetic analyses. RESULTS: We found the G2019S mutation in 6 patients and identified 2 new variants (Y2006H and T2031S) in 1 patient each. Their clinical features were similar to those of typical PD. All G2019S mutation carriers shared a common haplotype. CONCLUSIONS: The G2019S mutation is almost as frequent in sporadic cases (1.9%) as in previously reported familial cases (2.9%) in Europe and occurs in the same common founder. We identified 2 novel variants. Although the phenotype of LRRK2 mutation carriers closely resembles that of typical PD, the age at onset was younger (29 years in 1 patient) than previously described, and 3 patients were improved by deep brain stimulation.     

Analysis of the LRRK2 Gly2385Arg variant in Alzheimer's disease in Taiwan

ObjectiveTo analyze the Gly2385Arg (G2385R) mutation in Taiwanese Alzheimer's disease (AD) patients.BackgroundThe leucine-rich repeat kinase 2 (LRRK2) gene is well known to predispose subjects to Parkinson's disease (PD). The Gly2385Arg (G2385R) variant of LRRK2 is believed to be “East Asian”-specific, particularly in the Han Chinese population; however, whether the LRRK2 G2385R is associated with a risk of AD in pure Han-Chinese patients has not often been studied.MethodsA total of 209 AD patients (87 men, 122 women) and 180 age- and gender-matched controls were recruited and the demographic data of the AD patients were analyzed. Genotyping of the Gly2385Arg variant was studied using matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry.ResultsSubjects with the Gly2385Arg variant were all heterozygous carriers. The frequency of Gly2385Arg carriers did not differ significantly between the AD patients and controls (4.78% versus 4.44%, odds ratio = 1.04, 95% CI = 0.62–1.77, P = 0.87). In the AD patient group, the age of symptom onset, the length of education, or the MMSE score showed no significant differences between wild-type carriers and heterozygous variant carriers (P = 0.51, 0.43, and 0.09).ConclusionThe Gly2385Arg variant of LRRK2 may not be a major risk factor for AD in pure Han Chinese patient. Among the AD patients, Gly2385Arg carriers were not clinically different from wild-type carriers.     

LRRK2 Gly2019Ser penetrance in Arab-Berber patients from Tunisia: a case-control genetic study

BACKGROUND: Several genes have been implicated in the pathogenesis of Parkinson's disease (PD). The aim of this study was to define the clinical symptoms and age-associated cumulative incidence of the most frequent mutation associated with PD, LRRK2 Gly2019Ser. METHODS: 238 patients with sporadic PD and 371 unrelated control participants from the Arab-Berber population were screened at the Institut National de Neurologie, Tunis. Symptoms of PD were assessed using the Hoehn and Yahr scale, the unified Parkinson's disease rating scale, and the Epworth scale. Genotyping for LRRK2 6055G-->A, which causes the Gly2019Ser mutation, was done in all participants, and the age-specific cumulative incidence of PD was calculated by Kaplan-Meier analysis. FINDINGS: 30% of patients with PD in this case-control sample were carriers of LRRK2 Gly2019Ser. The age of onset of symptoms and the clinical presentation of patients with LRRK2 Gly2019Ser were similar to those of patients with idiopathic PD. Carriers of LRRK2 Gly2019Ser were 22.6 times (95% CI 10.2-50.1) more likely to be affected by PD than non-carriers. Tremor was the predominant symptom in LRRK2 Gly2019Ser carriers (92% [homozygotes] vs 75% [heterozygotes] vs 69% [non-carriers]; Cochran-Armitage trend test p=0.0587). Disease severity, response to treatment, and disease duration were similar among LRRK2 Gly2019Ser homozygotes, heterozygotes, and non-carriers (p=0.85). Disease penetrance in LRRK2 Gly2019Ser carriers ranged from less than 20% in those younger than 50 years to greater than 80% at 70 years. INTERPRETATION: The LRRK2 Gly2019Ser mutation in patients with PD is a useful aid to diagnosis. LRRK2 Gly2019Ser penetrance can vary but in most carriers PD seems an inevitable consequence of ageing. LRRK2 Gly2019Ser considerably increases susceptibility to neuronal degeneration, although the process might be mediated by many triggers. By contrast, idiopathic PD is rare before 50 years and the prevalence only increases to 4% in the oldest members of the population. FUNDING: GlaxoSmithKline; National Institutes of Health; and Mayo Foundation.     

LRRK2 G2019S mutation in Parkinson's disease: a neuropsychological and neuropsychiatric study in a large Algerian cohort

A series of 106 patients with isolated or familial Parkinsonism underwent clinical evaluation and genetic testing for the LRRK2 G2019S mutation which was identified in 34/106 patients (32%). Seventy one of them accepted to be evaluated for neuropsychological and neuropsychiatric studies with the aim to compare mutation carriers with non-carriers. For neuropsychological testing, comparisons between LRRK2 G2019S carriers and non-carriers were made after stratification according to the level of education: median and high school versus low level. Memory was investigated with the five words test, 2 novel tests with verbalized visual material dedicated to illiterate patients, the TNI-93 (nine pictures test), The TMA-93 (associative memory test), and digit spans (forward/backward). Cognitive analyse did not show major differences between the two groups of patients. Nevertheless, behavioral abnormalities, mostly depression and hallucinations, were more frequent in the LRRK2 G2019S carriers, suggesting the presence of a greater involvement of the limbic system in these patients. Sleep disorders which were also more common amongst mutation carriers than non-carriers might be related to depression.