Comprehensive mutational analysis of LRRK2 reveals variants supporting association with autosomal dominant Parkinson's disease

Parkinson's disease (PD) is a neurodegenerative disorder characterized by neurodegeneration, most notably of dopaminergic neurons in the substantia nigra. To date, six causative genes have been identified including LRRK2, whose mutations are the most frequent in autosomal dominant PD (Ad-PD). We conducted a comprehensive mutational analysis of LRRK2 in 30 Ad-PD (11 Japanese and 19 Caucasian) families employing a DNA microarray-based resequencing system and direct nucleotide sequence analysis, and identified 23 variants including two known mutations, p.G2019S and p.I1371V, in three Caucasian families and one Caucasian family, respectively, a novel putative pathogenic mutation, p.N1221K, in one Japanese family, and a known nonsynonymous variant, p.G2385R, in two Japanese families. Detailed analysis of the frequency of p.G2385R among 100 Japanese Ad-PD, 73 sporadic PD (sPD) and 238 controls revealed that the frequency of the p.G2385R variant was significantly higher in Ad-PD than in controls (allele frequency, 9.0 vs 2.1%) (χ(2)=16.32, P=5.34 × 10(-5)). The p.G2385R variant, however, did not show complete cosegregation with PD. In addition, the frequency of p.G2385R was also higher in sPD than in controls, although not significant (allele frequency, 3.4 vs 2.1%) (χ(2)=0.76, P=0.38). These observations support the possibility that p.G2385R is associated with an increased risk of PD.     

帕金森病致病基因LRRK2的研究进展

富含亮氨酸重复序列激酶2基因(1eucine-rich repeat kinase 2 gene,LRRK2)是家族性常染色体显性遗传性帕金森病8型的致病基因,其突变所致帕金森病具有与原发性帕金森病极为相似的临床表现,但神经病理改变却呈现出多样性.且突变类型、发生频率在不同人种间存在显著性差异.IRRK2在体内分布广泛,功能复杂,具有多个功能结构域,序列比对后推测,LRRK2可能作为一种对底物蛋白进行磷酸化修饰的多功能激酶或支架蛋白来发挥功能.对LRPK2正常生理功能及致病机制的研究,有助于深入探索帕金森病的发病机制以及寻求有效的防治措施.     

Comprehensive analysis of LRRK2 in publicly available Parkinson's disease cases and neurologically normal controls

Mutation of LRRK2, encoding dardarin, is the most common known genetic cause of Parkinson's disease (PD). The large size of this gene and the relative ease with which the most common mutations can be screened means that although more than 50 LRRK2 screening papers have been published, few have analyzed the entire coding sequence. Furthermore, no comprehensive sequence-based analysis has been performed on control samples. Here, we present sequencing of all coding exons in a series of 275 PD cases and 275 neurologically normal controls and analysis of the LRRK2 locus for whole gene multiplications or deletions. We also present case-control SNP association results using 74 SNPs genotyped across LRRK2. We identified six novel disease-associated missense mutations, including two that altered the same residue of the protein. These data and analysis of previously reported disease-segregating mutations shows that the majority of disease-causing mutations lie in the C-terminal half of the protein.     

LRRK2 R1441G in Spanish patients with Parkinson's disease

Pathogenic mutations in leucine-rich repeat kinase 2 (LRRK2; PARK8) have been implicated in autosomal dominant, late-onset Parkinson's disease (PD). The LRRK2 4321C>G (R1441G) mutation was originally identified in Spanish families originating from the Basque region. Within this ethnicity, Lrrk2 R1441G substitutions have been suggested as a frequent cause of disease. Herein we have assessed another referral-based series of 225 patients with PD from the neighboring region of Asturias, Northern Spain. The LRRK2 4321C>G mutation was found in 5 (2.7%) of sporadic, late-onset patients and was not present in control subjects. Although patients with a Lrrk2 R1441G substitution are apparently unrelated, they share a chromosome 12q12 haplotype not found in controls and indicative of a common founder.     

Evaluation of the role of LRRK2 gene in Parkinson's disease in an East Indian cohort

Leucine rich repeat kinase 2 (LRRK2) gene defects cause Parkinson's disease (PD). Recently, LRRK2 has also been shown by genome wide association (GWA) studies to be a susceptibility gene for the disease. In India mutations in LRRK2 is a rare cause of PD. We, therefore, genotyped 64 SNPs across LRRK2 in 161 control samples and finally studied 6 haplotype tagging SNPs for association-based study on 300 cases and 446 ethnically matched controls to explore the potential role of LRRK2 as a susceptibility gene in PD for East Indians. We did not find any significant allele/ genotype or haplotype associations with PD suggesting that common genetic variants within LRRK2 play limited role in modulating PD among East Indians. In addition, we also screened for the common mutations (viz. p.R1441C, p.R1441G, p.R1441H, p.Y1699C, p.G2019S), and a risk variant common among Asians (p.G2385R) but did not observe any of the above mentioned variants in our cohort. Our study, therefore, strongly suggests that LRRK2 has minimal role as a candidate and susceptibility gene in PD pathogenesis among East Indians.     

Comprehensive evaluation of common genetic variation within LRRK2 reveals evidence for association with sporadic Parkinson's disease

Parkinson's disease (PD) is a complex neurodegenerative disorder whose aetiologies are largely unknown. To date, mutations in six genes have been found causal for some rare familial forms of the disease and common variation within at least three of these is associated with the more common sporadic forms of PD. LRRK2 is the most recently identified familial PD gene, although its role in sporadic disease is unknown. In this study, we have performed the first comprehensive evaluation of common genetic variation within LRRK2 and investigated its contribution to risk of sporadic PD. We first characterized the linkage disequilibrium within LRRK2 using a panel of densely spaced SNPs across the gene. We then identified a subset of tagging-SNPs (tSNP) that capture the majority of common variation within LRRK2. Both single tSNP and tSNP haplotype analyses, using a large epidemiologically matched sporadic case-control series comprising 932 individuals, yielded significant evidence for disease association. We identified a haplotype that dramatically increases disease risk when present in two copies (OR=5.5, 95%CI=2.1-14.0, P=0.0001). Thus, we provide the first evidence that common genetic variation within LRRK2 contributes to the risk of sporadic PD in the Chinese population.     

Variants in the LRRK1 gene and susceptibility to Parkinson's disease in Norway

The discovery of LRRK2 gene mutations in late-onset Parkinson's disease (PD) has irrevocably established the role of genetics in the etiology of PD. The LRRK1 gene is the single homolog of LRRK2. A high degree of homology exists between LRRK1 and LRRK2, indicative of shared functions and/or pathways. One study has examined LRRK1 in familial parkinsonism by complete sequencing of the gene, reporting 4 novel non-synonymous coding variants within the LRRK1 gene. One of these variants (ss65713826) was identified in a Norwegian proband. We investigated whether five common polymorphisms or these recently identified coding changes within LRRK1 are associated with PD in the Norwegian population. Two rare coding variants ss65713826 and ss65713830 were more frequent in patients than controls. However, their identification in healthy controls and lack of co-segregation with disease suggests they may represent benign polymorphisms.     

A study of LRRK2 mutations and Parkinson's disease in Brazil

Mutations in the Leucine-rich repeat kinase 2 (LRRK2) gene are known as a common cause of Parkinson's disease (PD) among patients from different geographic origins. In this study, we evaluated the prevalence of LRRK2 mutations in exons 31 and 41 in a cohort of 154 consecutive, unrelated Brazilian patients with familial or sporadic PD, including early and late onset patients. The LRRK2 p.G2019S mutation was present in heterozygous state in three index cases (approximately 2%), and in three additional relatives. No carriers of this mutation were found among 250 control chromosomes. Clinically, all mutation-positive patients presented a typical PD phenotype and a good response to levodopa. Mutation segregation analysis in a large sibling showed incomplete penetrance of the p.G2019S. Our findings suggest that the LRRK2 p.G2019S mutation has a substantial contribution to PD susceptibility among Brazilian population and add new clues to current research of this disease.     

LRRK2 Pro755Leu variant in ethnic Chinese population with Parkinson's disease

Parkinson's disease (PD) is a common neurodegenerative disease resulting from complex interaction involving genetic and environmental risk factors on background of aging. In terms of genetic risk factors, recent studies provided a growing number of evidence for the idea that certain polymorphisms in familiar Parkinsonism genes may contribute to risk for sporadic PD in populations of specific ethnic backgrounds. To address this issue, a case-control study was conducted to determine the prevalence of LRRK2 Pro755Leu variant in 401 patients with sporadic PD and 398 unrelated healthy controls in Han population from mainland China. Heterozygous LRRK2 Pro755Leu variant was found in four patients and two healthy controls, but no statistical differences in genotypic or allelic frequencies between PD and control groups (genotype: P=0.686; allele: P=0.687) were detected. Furthermore, to evaluate its role in ethnic Chinese population, a meta-analysis was performed on Pro755Leu in population of Chinese ancestry throughout Asia. And it was detected at a similar frequency in PD and control cohort (Z=0.48, P=0.63, odds ratio=1.44, 95% CI: 0.32-6.40). Given these findings, it was quite reasonable to suppose that LRRK2 Pro755Leu variant rarely increased risk for PD in ethnic Chinese population in Asia.     

LRRK2基因G2019S突变帕金森病相关基因的生物信息学分析

目的 从分子水平揭示富亮氨酸重复激酶2（LRRK2)基因G2019S突变帕金森病的发病机制,为临床诊断及治疗提供新思路。 方法 在公共基因芯片数据库（GEO）中下载LRRK2基因G2019S突变帕金森病的相关基因芯片数据（GSE22491）,其中LRRK2(G2019S)突变帕金森病样本10 例,正常控制组样本8 例,利用Qlucore Omics Explorer（QOE）3.0 软件、DAVID、STRING等在线分析软件对LRRK2基因G2019S突变帕金森病差异基因进行生物信息学分析。结果 QOE3.0分析筛选出1752个LRRK2基因G2019S突变帕金森病差异基因,其中上调191个,下调1561个。对其进行生物信息学分析发现,SKP2、RBX1、SKP1、CUL1、CUL4A 等基因以及核糖体信号通路、氧化磷酸化信号通路、蛋白酶体信号通路、白细胞跨内皮迁移信号通路、磷酸戊糖途径信号通路、枸橼酸信号通路、Fcγ受体（FcγR）介导的吞噬通路等在LRRK2基因G2019S突变帕金森病的发生发展中可能起着重要作用。 结论 通过生物信息学分析LRRK2基因G2019S突变帕金森病相关基因芯片数据,提示LRRK2基因G2019S突变帕金森病发病是多种基因、多种分子机制相互作用的结果,对相关分子机制的进一步分析有利于揭示LRRK2基因G2019S突变帕金森病的发病机制。     

LRRK2 in Parkinson's disease – drawing the curtain of penetrance: a commentary

Exacerbations are a major cause of morbidity and mortality in chronic obstructive pulmonary disease. Exacerbations can be of bacterial, viral or mixed etiology, with bacteria involved in 50% of exacerbations. Consequently, current management of exacerbations frequently involves the use of antibiotics. The paper by Puhan et al published this month in BMC Medicine examines the benefit of antibiotics in placebo-controlled trials in mild to moderate outpatient exacerbations. The authors use a meta-analytic approach and rightly conclude that more trials are needed in this area. However, the heterogeneity of chronic obstructive pulmonary disease patients and exacerbations and the limited end-points in past trials do not allow firm conclusions to be drawn about antibiotic use in outpatient exacerbations based on this meta-analysis. Future trials need to take into account this heterogeneity as well as incorporate novel end-points to address this important issue.     

Testing association between LRRK2 and Parkinson's disease and investigating linkage disequilibrium

Background

We and others recently identified the gene underlying PARK8 linked Parkinson''s disease (PD). This gene, LRRK2, contains mutations that cause an autosomal dominant PD, including a mutation, G2019S, which is the most common PD causing mutation identified to date. Common genetic variability in genes that contain PD causing mutations has previously been implicated as a risk factor for typical sporadic disease.

Methods

We undertook a case‐control association analysis of LRRK2 in two independent European PD cohorts using 31 tagging single nucleotide polymorphisms (tSNPs) and five potentially functional SNPs. To assess the structure of this locus in different populations, we have performed linkage disequilibrium (LD) analysis using these variants in a human diversity panel.

Results

We show that common genetic variability in LRRK2 is not associated with risk for PD in the European populations studied here. We also show inter‐population variability in the strength of LD across this locus.

Conclusions

To our knowledge this is the first comprehensive analysis of common variability within LRRK2 as a risk factor for PD.     

LRRK2 G2019S is a common mutation in Spanish patients with late-onset Parkinson's disease

Mutations in the leucine-rich repat kinase 2 (LRRK2) gene have been shown to cause both autosomal dominant and sporadic Parkinson's disease (PD). The common G2019S mutation shows wide geographical distribution while R1441G has been only reported in Northern Spain. The overall frequency of these mutations remains to be established. To determine the prevalence of G2019S and R1441G mutations in our population of Cantabria (Northern Spain), we recruited 105 consecutive PD patients and 310 controls and conducted genetic analysis of these mutations. G2019S was detected in eight late-onset patients (7.6%). Five of them had no relevant family history. R1441G was not detected in any of our study subjects. The prevalence of G2019S mutation in unselected late-onset PD patients might be higher than previously reported: 3/16 (18.7%) of familial PD and 5/82 (6.1%) of sporadic PD.     

Absence/rarity of commonly reported LRRK2 mutations in Indian Parkinson's disease patients

Recent discovery of pathogenic mutations in the leucine-rich repeat kinase 2 (LRRK2) gene in Parkinson's disease (PD) patients in different ethnic groups have raised a hope of diagnostic screening and genetic counseling. We investigated the six most commonly reported mutations in LRRK2 gene among Indian PD patients, using PCR-RFLP method. Mutations G2019S, R1441C, R1441G, and R1441H were screened in 1012 individuals (PD, 800; controls, 212) while mutations I2012T and I2020T were screened in 748 PD patients. We did not observe any of these six mutations in this study sample except in a single female young onset PD patient who showed a heterozygous G2019S mutation. The absence of mutations was reconfirmed by sequencing of probands from several autosomal dominant PD families. Our observations suggest that these mutations may be a rare cause of PD among Indians and therefore of little help for diagnostic screening and genetic counseling for Indian PD patients.