Mutations in the glucocerebrosidase gene are common in patients with Parkinson's disease from Eastern Canada

Background: Mutations in the β-glucocerebrosidase gene (GBA) have been implicated as a risk factor for Parkinson's disease (PD). However, GBA mutations in PD patients of different ethnic origins were reported to be inconsistent. Methods: We sequenced all exons of the GBA gene in 225 PD patients and 110 control individuals from Eastern Canada. Result: Two novel GBA variants of c.-119 A/G and S(-35)N, five known GBA mutations of R120W, N370S, L444P, RecNciI and RecTL mutation (del55/D409H/RecNciI) as well as two non-pathological variants of E326K and T369M were identified from PD patients while only one mutation of S13L and two non-pathological variants of E326K and T369M were found in the control individuals. The frequency of GBA mutations within PD patients (4.4%) is 4.8 times higher than the 0.91% observed in control individuals (X² = 2.91, p = 0.088; odds ratio = 4.835; 95% confidence interval = 2.524–9.123). The most common mutations of N370S and L444P accounted for 36.0% (9/25) of all the GBA mutations in this Eastern Canadian PD cohort. The frequency (6.67%) of E326K and T369M in PD patients is comparable to 7.27% in control individuals (X² = 0.042, p = 0.8376), further supporting that these two variants have no pathological effects on PD. Phenotype analysis showed that no significant difference in family history, age at onset and cognitive impairment was identified between the GBA mutation carriers and non-GBA mutation carriers. Conclusion: GBA mutations were found to be a common genetic risk factor for PD in Eastern Canadian patients.     

Glucocerebrosidase Gene L444P mutation is a risk factor for Parkinson's disease in Chinese population

An association between mutations in the glucocerebrosidase (GBA) gene and Parkinson's disease (PD) has been reported in several populations. We searched for four common GBA mutations (L444P, F213I, R353W, and N370S) in 402 Chinese PD patients and 413 age‐ and sex‐matched controls. In the PD cohort, 11 patients were found carrying a heterozygous GBA mutation and all of them had the L444P mutation. Heterozygous GBA mutations were detected none in controls. The GBA gene L444P mutation was detected at a significantly higher frequency among PD patients (11/402 = 2.74%), when compared with the control group (0/413): P = 0.0007. To evaluate the possible role of the GBA gene L444P mutation in PD in Ashkenazi Jewish and non‐Jewish populations, we conducted a meta‐analysis on the topic. In the Chinese population, the GBA gene L444P mutation was detected at a significantly higher frequency among PD patients, when compared with the control group: Z = 3.83, P = 0.0001, OR = 8.42, confidence interval = 95%, 2.83–25.06. In the non‐Jewish populations, the difference was obviously significant: Z = 5.76, P < 0.00001, OR = 8.82, confidence interval = 95%, 4.21–18.48. The results suggest that the GBA gene L444P mutation appears to be a risk factor for PD in Chinese population. © 2010 Movement Disorder Society     

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.     

Glucocerebrosidase gene mutations are associated with Parkinson's disease in southern Italy

Recent studies have reported an association between the glucocerebrosidase (GBA) gene and Parkinson's disease (PD). To elucidate the role of this gene in our population, we screened 395 PD patients and 483 controls from southern Italy for the N370S and the L444P mutations. We found 11 patients (2.8%) carrying a heterozygous mutant GBA allele, whereas only one control subject (0.2%) had a heterozygous substitution (P = 0.0018). These results strongly suggest that Italian carriers of a GBA mutation have an increased risk of developing PD. © 2007 Movement Disorder Society     

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     

Homozygosity for the <Emphasis Type="Italic">MTX1</Emphasis> c.184T>A (p.S63T) alteration modifies the age of onset in <Emphasis Type="Italic">GBA</Emphasis>-associated Parkinson's disease

A strong association was established between the GBA gene and Parkinson's disease (PD) worldwide. The most frequent GBA mutation among the Ashkenazi population (p.N370S) was previously associated with the c.1051T>C (p.F351L) alteration in the closely located MTX1 gene. We further studied the association between these two genes and its possible effect on PD. The entire coding region and exon–intron boundaries of MTX1 were analyzed in 81 PD patient carriers of GBA mutations, 15 healthy controls that carry GBA mutations, and in 25 non-carrier patients. Among them, the MTX1 c.184T>A (p.S63T) variation was detected in 93% of GBA mutation carriers (both patients and healthy controls) and in 64% of non-carrier patients (p = 0.0008). This alteration was analyzed in 600 consecutively recruited Ashkenazi PD patients and in 353 controls, all genotyped for the LRRK2 p.G2019S and GBA founder mutations. A significantly higher frequency of the MTX1 c.184A allele was found in carriers of GBA mutations compared to non-carriers (0.67 and 0.45, respectively, p < 0.0001). The homozygous MTX1 c.184A/A genotype was associated with a significantly earlier age of motor symptoms onset in patients with GBA mutations compared to other groups of patients tested (5.1–5.9 years younger, p = 0.002–0.01). A significantly higher frequency of early-onset PD (<50 years) was detected among patients carrying both GBA mutation and the homozygous MTX1 c.184A/A genotype (35.9%, compared to 13.6–17.5%, p = 0.028). Our results raise the possibility that alteration on the opposite allele, which is in trans to the GBA mutant allele, may affect the clinical course of GBA-associated 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.     

LRRK2 mutations and risk variants in Japanese patients with Parkinson's disease

Mutations in the leucine‐rich repeat kinase 2 (LRRK2) gene are the most common genetic determinant of Parkinson's disease (PD) in European‐derived populations, but far less is known about LRRK2 mutations and susceptibility alleles in Asians. To address this issue, we sequenced the LRRK2 coding region in 36 patients with familial PD, then genotyped variants of interest in an additional 595 PD cases and 1,641 controls who were all of Japanese ancestry. We also performed a meta‐analysis of studies on G2385R, a polymorphism previously reported to associate with PD. One pathogenic (G2019S) and one putative pathogenic (R1067Q) mutation were each observed in two patients with sporadic PD. The overall mutation frequency among patients was 0.6%. G2385R was highly associated with PD under a dominant model in our dataset (adjusted OR, 1.83; 95% CI, 1.31–2.54; P = 3.3 × 10^?4) and similar results were seen in the meta‐analysis (summary OR assuming fixed effects, 2.55; 95% CI, 2.10–3.10). G2385R represents the first consistently replicated common PD susceptibility variant in a non‐European population and its effect size is substantially greater than that reported for other well‐validated genetic risk factors for the disease. However, LRRK2 mutations appear to be rare among Japanese patients with PD. © 2009 Movement Disorder Society     

Glucocerebrosidase gene mutation is a risk factor for early onset of Parkinson disease among Taiwanese

Background

Mutations in the glucocerebrosidase (GBA) gene have recently been identified as contributing to the development of Parkinson disease (PD) in Ashkenazi Jews.

Methods

To investigate whether this finding can be confirmed in a Taiwanese population, we conducted a case control study in a cohort of 518 PD patients and 339 controls for the three common GBA mutations in Taiwan, L444P, RecNciI and R120W, using PCR restriction enzyme assay and DNA sequencing.

Results

Heterozygous GBA mutations were detected in 16 PD patients (3.1%) and four controls (1.2%). Although this difference was not statistically significant (p = 0.0703), the average age at disease onset of the 16 PD patients (50.6 (12.3) years) was significantly younger than that of the total patient group (63.8 (10.5) years; p = 0.0007) and the non‐carrier patient group (64.2 (10.2) years; p = 0.0005). After stratification by age, the frequency of mutation carriers was significantly higher for the early onset PD (EOPD, age at onset ⩽50 years) group than for age matched controls (12.9% vs 1.8%; p = 0.0335) and there was a trend towards an increased risk of the mutation carrier with EOPD (odds ratio 8.30; 95% CI 1.45 to 156.53). Clinically, all 16 patients carrying a GBA mutation presented with a typical parkinsonian phenotype and experienced a good or excellent response to levodopa.

Conclusions

Mutations of the GBA gene may be associated with the development of EOPD in Taiwan.Parkinson disease (PD) is the second most common neurodegenerative disease, characterised by resting tremor, bradykinesia, rigidity and postural instability. These symptoms result predominantly from selective loss of dopaminergic neurons in the substantia nigra pars compacta and subsequent depletion of dopamine in their projections. Pathologically, PD is defined by the presence of Lewy bodies, intracellular neuronal inclusions in the substantia nigra pars compacta and other brain sites.¹ The pathogenesis of PD remains unclear. An interaction between environmental factors and genetic predisposition is thought to contribute to disease development.² Causal mutations in the genes for α‐synuclein, parkin, DJ‐1, PTEN induced kinase 1 and leucine‐rich repeat kinase‐2 have been identified.³ However, mutations of these genes do not account for the occurrence of PD in all patients. Identifying novel PD genetic risk factors is important to understand its pathogenesis.Gaucher disease (GD) is a recessively inherited glycolipid storage disorder caused by deficiency of the lysosomal enzyme glucocerebrosidase (GBA).⁴ Clinically, GD is characterised by vast phenotypic heterogeneity and is classified into three types based on the severity of associated neurological symptoms.⁵ Recent studies have reported genetic association between GD and PD.^6,7 The molecular pathogenic mechanism causing PD in GBA mutation carriers remains unclear.The gene encoding GBA has been localised at chromosome 1q21, and there is a highly homologous pseudogene (GBAP) sequence located 16 kb downstream.⁸ More than 200 mutations, including point mutations, deletions and rearrangements, have been identified in this gene (http://www.hgmd.cf.ac.uk/ac/gene.php?gene = GBA). Mutation analysis of GD patients in Taiwan has reported three common mutations, L444P, RecNciI (the recombination allele between the GBA and GBAP genes) and R120W, that account for 87% of Gaucher chromosomes.⁹ R120W was defined as a mild mutation associated with non‐neuropathic GD in Taiwanese.⁹To investigate the possible association between the GBA gene mutations and PD in Taiwan, we examined the frequency of these three GBA mutations to determine whether the GBA mutations are genetically associated with PD, using a case control study design.     

Analysis of PARK genes in a Korean cohort of early-onset Parkinson disease

Mutations in five PARK genes (SNCA, PARKIN, DJ-1, PINK1, and LRRK2) are well-established genetic causes of Parkinson disease (PD). Recently, G2385R substitution in LRRK2 has been determined as a susceptibility allele in Asian PD. The objective of this study is to determine the frequency of mutations in these PARK genes in a Korean early-onset Parkinson disease (EOPD) cohort. The authors sequenced 35 exons in SNCA, PARKIN, DJ-1, PINK1, and LRRK2 in 72 unrelated EOPD (age-at-onset ≤50) recruited from ten movement disorders clinics in South Korea. Gene dosage change of the aforementioned genes was studied using multiple ligation-dependent probe amplification. We found four patients with PARKIN mutations, which were homozygous deletion of exon 4, compound heterozygous deletion of exon 2 and exon 4, heterozygous deletion of exon 4, and heterozygous nonsense mutation (Q40X). Four patients had PINK1 mutations; a compound heterozygous mutation (N367S and K520RfsX522) and three heterozygous mutations (G32R, R279H, and F385L). A missense mutation of SNCA (A53T) was found in a familial PD with autosomal dominant inheritance. Nine patients (12.5%) had heterozygous G2385R polymorphism of LRRK2, whereas none had G2019S mutation. However, no mutations were detected in DJ-1 and UCHL1 in our series. We identified genetic variants in PARKIN, PINK1, LRRK2, and SNCA as a cause or genetic risk factors for PD in 25% of Korean EOPD, and mutation of PARKIN was the most common genetic cause. Jung Mi Choi and Myoung Soo Woo equally contributed to this work.     

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.     

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.     

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.     

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     

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 % CI 2.216–70.942, 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 % CI 1.074–15.864). 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.     

Lack of association between LRRK2 G2385R and cognitive dysfunction in Korean patients with Parkinson’s disease

Aside from the glucocerebrosidase gene, the genetic risk factors for cognitive decline in Parkinson’s disease (PD) are controversial. We investigated whether the G2385R polymorphism in leucine-rich repeat kinase 2 gene (LRRK2), a risk variant for the development of PD in East Asians, is associated with cognitive dysfunction in PD. We recruited 299 PD patients, consisting of 23 carriers and 276 non-carriers of LRRK2 G2385R, from 14 centers. Global cognitive function was assessed using the Mini-Mental State Examination (MMSE) or the Montreal Cognitive Assessment (MoCA). PD with cognitive dysfunction was defined as an MMSE Z score that, adjusting for age at study entry and years of education, was below -1.0 standard deviations.In multivariate analysis, PD duration, age at study entry and depression were significant risk factors for cognitive dysfunction as assessed by MMSE performance or the MoCA. In linear regression analysis of the association between MMSE Z scores and PD duration, there was no significant difference associated with the LRRK2 G2385R genotype. The interaction terms between PD duration and the LRRK2 G2385R genotype were not significant for the MMSE Z score but were significant for the MoCA. In conclusion, the LRRK2 G2385R genotype may not be associated with cognitive dysfunction in PD.     

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.     

Genetic risk factors in Finnish patients with Parkinson's disease

IntroductionVariation contributing to the risk of Parkinson's disease (PD) has been identified in several genes and at several loci including GBA, SMPD1, LRRK2, POLG1, CHCHD10 and MAPT, but the frequencies of risk variants seem to vary according to ethnic background. Our aim was to analyze how variation in these genes contributes to PD in the Finnish population.MethodsThe subjects consisted of 527 Finnish patients with early-onset PD, 325 patients with late-onset PD and 403 population controls. We screened for known genetic risk variants in GBA, SMPD1, LRRK2, POLG1, CHCHD10 and MAPT. In addition, DNA from 225 patients with early-onset Parkinson's disease was subjected to whole exome sequencing (WES).ResultsWe detected a significant difference in the length variation of the CAG repeat in POLG1 between patients with early-onset PD compared to controls. The p.N370S and p.L444P variants in GBA contributed to a relative risk of 3.8 in early-onset PD and 2.5 in late-onset PD. WES revealed five variants in LRRK2 and SMPD1 that were found in the patients but not in the Finnish ExAC sequences. These are possible risk variants that require further confirmation. The p.G2019S variant in LRRK2, common in North African Arabs and Ashkenazi Jews, was not detected in any of the 849 PD patients.ConclusionsThe POLG1 CAG repeat length variation and the GBA p.L444P variant are associated with PD in the Finnish population.     

Olfactory Dysfunction in Parkinson’s Disease Patients with the <Emphasis Type="Italic">LRRK2</Emphasis> 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.     

Glucocerebrosidase mutations in primary parkinsonism

IntroductionMutations in the lysosomal glucocerebrosidase (GBA) gene increase the risk of Parkinson's Disease (PD). We determined the frequency and relative risk of major GBA mutations in a large series of Italian patients with primary parkinsonism.MethodsWe studied 2766 unrelated consecutive patients with clinical diagnosis of primary degenerative parkinsonism (including 2350 PD), and 1111 controls. The entire cohort was screened for mutations in GBA exons 9 and 10, covering approximately 70% of mutations, including the two most frequent defects, p.N370S and p.L444P.ResultsFour known mutations were identified in heterozygous state: 3 missense mutations (p.N370S, p.L444P, and p.D443N), and the splicing mutation IVS10+1G>T, which results in the in-frame exon-10 skipping. Molecular characterization of 2 additional rare variants, potentially interfering with splicing, suggested a neutral effect. GBA mutations were more frequent in PD (4.5%, RR = 7.2, CI = 3.3–15.3) and in Dementia with Lewy Bodies (DLB) (13.8%, RR = 21.9, CI = 6.8–70.7) than in controls (0.63%). but not in the other forms of parkinsonism such as Progressive Supranuclear Palsy (PSP, 2%), and Corticobasal Degeneration (CBD, 0%). Considering only the PD group, GBA-carriers were younger at onset (52 ± 10 vs. 57 ± 10 years, P < 0.0001) and were more likely to have a positive family history of PD (34% vs. 20%, P < 0.001).ConclusionGBA dysfunction is relevant for synucleinopathies, such as PD and DLB, except for MSA, in which pathology involves oligodendrocytes, and the tauopathies PSP and CBD. The risk of developing DLB is three-fold higher than PD, suggesting a more aggressive phenotype.