GIGYF2 Asn56Ser mutation is rare in Chinese Parkinson's disease patients

Grb10-Interacting GYF Protein-2 gene (GIGYF2) has been suggested as a candidate gene for PARK11 locus since seven different GIGYF2 missense mutations were identified in familial Parkinson's disease (PD) patients of European descent. To evaluate the frequency and distribution of GIGYF2 Asn56Ser mutation in Chinese PD patients, we analyzed 469 patients with PD from mainland China, including 36 cases with familial PD and 433 cases with sporadic PD. A total of 451 subjects without neurological disorders from the same region in China were set as a control group. The result showed that the GIGYF2 Asn56Ser mutation was not present in all subjects. Our finding suggests that the GIGYF2 Asn56Ser mutation is rare in Chinese PD patients.     

No evidence for pathogenic role of GIGYF2 mutation in Parkinson disease in Japanese patients

Grb10-Interacting GYF Protein-2 (GIGYF2) is a candidate gene for PARK11 locus. To date, seven different GIGYF2 missense mutations have been identified in patients with familial Parkinson disease (PD) of European descent. To clarify the pathogenic role of GIGYF2 in PD, we analyzed the frequency of GIGYF2 mutations in 389 Japanese patients with PD (including 93 patients with late-onset familial PD, 276 with sporadic PD, and 20 with a single heterozygous mutation in the PD-associated genes), and 336 Japanese normal controls, by direct sequencing and/or high-resolution melting analysis. None of the reported GIGYF2 mutations or digenic mutations were detected. Two novel non-synonymous variants were identified (p.Q1211delQ and p.H1023Q), however, we could not determine their roles in PD. In summary, we found no evidence for PD-associated roles of GIGYF2 mutations. Our data suggest that GIGYF2 is unlikely to play a major role in PD in Japanese patients, similar to other populations.     

VPS35 Asp620Asn and EIF4G1 Arg1205His mutations are rare in Parkinson disease from Southwest China

The Asp620Asn mutation in the vacuolar protein sorting protein 35 (VPS35) gene and the Arg1205His mutation in the eukaryotic translation initiation factor 4 gamma 1 (EIF4G1) gene were identified in autosomal dominant late-onset familial and sporadic Parkinson disease (PD) patients in a Caucasian population. However, the frequencies of these 2 mutations among Chinese PD patients are unknown. We examined these mutations in a large cohort consisting of 609 PD patients and 600 healthy control subjects from Southwest China. Our results suggest that the Asp620Asn mutation in VPS35 and the Arg1205His mutation in EIF4G1 do not play a role in PD in the Southwest China population. The novel Arg1205Cys mutation in EIF4G1 detected in the current study should be further studied among other Asian patients.     

GIGYF2 has no major role in Parkinson genetic etiology in a Belgian population

Missense mutations were identified in the Grb10-Interacting GYF Protein-2 gene (GIGYF2), located in the chromosomal region 2q36-q37, in familial Parkinson disease (PD) patients of European descent. To determine the contribution of GIGYF2 mutations in an extended (N = 305) Belgian series of both familial and sporadic PD patients, we sequenced all 32 coding and non-coding exons of GIGYF2. In three sporadic PD patients we identified two novel heterozygous missense mutations (c.1907A>G, p.Tyr636Cys and c.2501G>A, p.Arg834Gln), that were absent from control individuals (N = 360). However, since we lack genetic as well as functional data supporting their pathogenic nature, we cannot exclude that these variants are benign polymorphisms. Together, our results do not support a role for GIGYF2 in the genetic etiology of Belgian PD.     

Novel GIGYF2 gene variants in patients with Parkinson's disease in Chinese population

The Grb10-Interacting GYF Protein-2 gene (GIGYF2), located in the chromosomal region 2q36-q37, has been reported as a PARK11 gene with a causal role in familial Parkinson's disease (PD) in Italian and French populations. However, there is no comprehensive study of GIGYF2 gene conducted in Chinese patients with PD from mainland China. The 27 coding exons and intron/exon boundaries of the GIGYF2 gene were sequenced in 300 sporadic patients with Parkinson's disease. Eight heterozygous and one homozygous novel missense variants were identified in nine patients with PD, and not in 300 controls. p.Leu580Phe locates in the GYF domain and might interrupt the potentially function of GIGYF2 protein. Another variant Gln979stop encodes a truncated protein. In conclusion, we identified nine novel variants in GIGYF2 gene, which might be associated with PD in the Chinese population.     

DRD3 Ser9Gly and HS1BP3 Ala265Gly are not associated with Parkinson disease

Variants in the dopamine receptor D3 (DRD3) and HCLS1 binding protein 3 (HS1BP3) have been nominated as risk factors for essential tremor (ET). Although ET and Parkinson disease (PD) are considered different entities, they have many overlapping clinical and pathological features. We aim to evaluate the role of the Ser9Gly variant in DRD3 and Ala265Gly in HS1BP3 in PD development. To this end, we genotyped these two variants in a PD matched case–control series from the United States. Statistical analysis failed to identify significant differences in the frequency of these variants between the case and control groups; therefore our results do not support a role for these DRD3 and HS1BP3 variants in PD.     

Low frequency of common LRRK2 mutations in Mexican patients with Parkinson's disease

Mutations in leucine-rich repeat kinase 2 gene (LRRK2) account for as much as 5–6% of familial Parkinson's disease (PD) and 1–2% of sporadic PD. These mutations represent the most frequent cause of autosomal dominant PD, particularly in certain ethnic groups. In this first report concerning LRRK2 mutations in Mexican-mestizos, we screened 319 consecutive PD patients (186 males; 133 females; mean age at onset: 52.4 years) for LRRK2 mutations in exons 31 and 41 and for the mutation in exon 35, which produces the Y1699C substitution. Three (0.94%) patients, two with sporadic PD and one with familial PD (disease mean age at onset, 53.3 years), were heterozygous for LRRK2 mutations. Of these three, two patients had one of two different mutations in exon 31 (R1441G and R1441H, respectively); the other patient carried the G2019S mutation in exon 41. The Y1699C mutation was absent from this PD sample. Four additional subjects, unaffected relatives of one PD patient with a mutation in LRRK2, were subsequently genetically tested. None of the three LRRK2 mutations identified was present in 200 neurologically healthy Mexican control individuals. These findings have important implications for molecular testing of LRRK2 mutations in Mexican PD patients.     

Mutational analysis of GIGYF2, ATP13A2 and GBA genes in Brazilian patients with early-onset Parkinson's disease

In the last decade, several genes have been linked to Parkinson's disease (PD), including GIGYF2, ATP13A2 and GBA. To explore whether mutations in these genes contribute to development of PD in the Brazilian population, we screened 110 patients with early-onset PD. No clearly pathogenic mutations were identified in ATP13A2 and GIGYF2. In contrast, we identified a significantly higher frequency of known pathogenic mutations in GBA gene among the PD cases (6/110 = 5.4%) when compared to the control group (0/155) (P = 0.0047). Our results strongly support an association between GBA gene mutations and an increased risk of PD. Mutations in GIGYF2 and ATP13A2 do not seem to represent a risk factor to the development of PD in the Brazilian population. Considering the scarcity of studies on GIGYF2, ATP13A2 and GBA mutation frequency in Latin American countries, we present significant data about the contribution of these genes to PD susceptibility.     

LINGO1 rs9652490 variant in Parkinson disease patients

Essential tremor (ET) has been hypothesized to be a risk factor for the development of Parkinson disease (PD). Recently, rs9652490 variant in the leucine-rich repeat and Ig domain containing 1 gene (LINGO1) was found to be associated with ET susceptibility. To evaluate whether the same variant is associated also with PD susceptibility, we investigated the association between the LINGO1 rs9652490 variant and PD phenotype in Caucasian and Chinese PD subjects. We found no significant differences in genotypic and allele distribution between patients and control subjects (χ(2)=1.931, p=0.381 for genotypic distribution; χ(2)=0.001, p=0.973 for allele distribution), suggesting this variant is not associated with PD.     

Mutational screening and zebrafish functional analysis of GIGYF2 as a Parkinson-disease gene

The Grb10-Interacting GYF Protein-2 (GIGYF2) gene has been proposed as the Parkinson-disease (PD) gene underlying the PARK11 locus. However, association of GIGYF2 with PD has been challenged and a functional validation of GIGYF2 mutations is lacking.In this frame, we performed a mutational screening of GIGYF2 in an Italian PD cohort. Exons containing known mutations were analyzed in 552 cases and 552 controls. Thereafter, a subset of 184 familial PD cases and controls were subjected to a full coding-exon screening. These analyses identified 8 missense variations in 9 individuals (4 cases, 5 controls).Furthermore, we developed a zebrafish model of gigyf2 deficiency. Abrogation of gigyf2 function in zebrafish embryos did not lead to a drastic cell loss in diencephalic dopaminergic (DA) neuron clusters, suggesting that gigyf2 is not required for DA neuron differentiation. Notably, gigyf2 functional abrogation did not increase diencephalic DA neurons susceptibility to the PD-inducing drug MPP+.These data, together with those recently reported by other groups, suggest that GIGYF2 is unlikely to be the PARK11 gene.     

DYT1 mutations in early onset primary torsion dystonia and Parkinson disease patients in Chinese populations

Torsion dystonia is an autosomal dominant movement disorder characterized by involuntary, repetitive muscle contractions and twisted postures. The most severe early onset form of dystonia has been linked to mutations in the human DYT1 (TOR1A) gene encoding a protein termed torsinA. Moreover, dystonia and Parkinson disease share the common feature of reduced dopamine neurotransmission in the striatum, so we assumed that mutations in the DYT1 gene might have the same role in cases of early onset primary torsion dystonia (EOPTD) and early onset Parkinson disease (EOPD) that present dystonia. In this present study, 17 patients with EOPTD, 221 patients with EOPD and 164 control subjects were screened for mutations of the DYT1 gene by denaturing high performance liquid chromatography (DHPLC), polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis and DNA sequencing. Our results showed that the GAG deletion was identified in 7 EOPTD patients, which results in Glu302del of DYT1 gene. No mutations were found in EOPD patients and control subjects. By carefully reviewing the available literature on studies of sporadic, non-Ashkenazi Jewish populations, the results showed that the prevalence rate of DYT1 mutation was not significantly different (p = 0.267) between European (27.3%) and Asian (22.2%) patients with early onset primary torsion dystonia.     

Heterozygous TREM2 mutations in frontotemporal dementia

A causative association was recently demonstrated between homozygous TREM2 mutations and frontotemporal dementia (FTD)-like syndrome and between heterozygous TREM2 exon2 genetic variations and late-onset Alzheimer's disease (AD). The objective of this study was to evaluate whether heterozygous TREM2 genetic variations might be associated to the risk of FTD. TREM2 exon 2 was sequenced in a group of 1030 subjects—namely, 352 patients fulfilling clinical criteria for FTD, 484 healthy control subjects (HCs), and 194 patients with AD. The mutation frequency and the associated clinical characteristics were analyzed. We identified 8 missense and nonsense mutations in TREM2 exon 2 in 24 subjects. These mutations were more frequent in patients with FTD than in HCs (4.0% vs. 1.0%, p = 0.005). In particular, TREM2 Q33X, R47H, T66M, and S116C mutations were found in FTD and were absent in HCs. These mutations were associated with either the semantic variant of primary progressive aphasia or the behavioral variant FTD phenotypes. The FTD and AD groups were not significantly different with regard to TREM2 genetic variation frequency (AD: 2.6%, p = 0.39). Heterozygous TREM2 mutations modulate the risk of FTD in addition to increasing susceptibility to AD. Additional studies are warranted to investigate the possible role of these mutations in the pathogenesis of neurodegenerative disorders.     

成都地区汉族人群PPARGC1A基因Thr394Thr位点G/A多态性与2型糖尿病及胰岛素抵抗的相关性研究

目的 了解中国成都地区汉族人群过氧化物酶体增殖物激活受体γ辅助激活因子-1α基因(peroxisome proliferator-activated receptor gamma,coactivator 1 alpha,PPARGC1A;又名PGC-1α)Thr394Thr位核苷酸G/A的基因型分布,探讨该多态性与2型糖尿病(type 2 diabetes mellitus,T2DM)、胰岛素抵抗及其他代谢异常的关系.方法 应用聚合酶链反应-限制性片段长度多态性技术检测151例无亲缘关系的T2DM患者和156名糖耐量正常对照者PPARGC1A基因Thr394Thr位核苷酸G/A多态性.所有研究对象均测定血糖、胰岛素、血脂,测量身高、体重、腰围、血压.结果 与正常对照组相比,T2DM组的体重指数、腰围、血压、甘油三酯水平均显著增高(P＜0.05),而高密度脂蛋白胆固醇(high density lipoprotein-cholesterol,HDL-C)水平显著降低(P＜0.05).A等位基因的频率在T2DM及正常对照组分别为22.5%、18.6%,AG基因型频率在两组分别为43.7%、37.2%,差异无统计学意义.在T2DM组中,AA+AG基因型的空腹胰岛素、稳态模型评估法胰岛素抵抗指数(homeostasis model aseessment-insulin resistance,HOMA-IR)及腰围明显高于GG基因型,HDL-C显著低于GG基因型(P＜0.05).无论T2DM和正常对照,A等位基因携带者HOMA-IR明显高于GG者.结论 PPARGC1A基因Thr394Thr位核苷酸G/A多态性与胰岛素抵抗存在明显相关,并可能与T2DM患者中心性肥胖及低HDL-C水平相关,其与T2DM发病的关系有待进一步研究.     

Genetic analysis of LRRK2 P755L variant in Caucasian patients with Parkinson's disease

Parkinson's disease (PD) is the second most common neurodegenerative disease with major clinical features of bradykinesia, rigidity, resting tremor, and postural instability. Mutations in the leucine-rich repeat kinase 2 gene (LRRK2) have been identified both in familial and sporadic cases of PD. Recently, a P755L variant in the LRRK2 gene has been found to be responsible for 2% of Chinese patients with sporadic PD. To evaluate the frequency of the LRRK2 P755L variant in North American Caucasian patients with PD, we screened 426 PD patients and 37 additional patients with the combination of PD and essential tremor (ET) from our Parkinson Disease Center and Movement Clinic at Baylor College of Medicine. No P755L variant was found in our PD cohort. Therefore, we conclude that LRKK2 P755L variant is a rare cause of Caucasian PD and has no diagnostic utility in genetic testing of this population of patients.     

DNAJ mutations are rare in Chinese Parkinson's disease patients and controls

Mutations in DNAJC13, DNAJC6 and DNAJC5 have been implicated in Parkinson's disease (PD). To determine if rare coding variants in these genes play a role in PD risk in the Chinese population, we sequenced all coding exons of the three genes in 99 early-onset PD cases and 99 controls, and genotyped 8 missense variants in another 711 PD cases and 539 controls. Besides two common missense variants that did not show association with PD, the remaining missense variants were extremely rare (<0.5%), found in healthy population controls and did not show enrichment in PD cases. Our results suggest that missense mutations in DNAJC13, DNAJC5 and DNAJC6 do not play a major role in PD in the Chinese population.     

VPS35 and EIF4G1 mutations are rare in Parkinson's disease among Indians

Mutations in 2 genes, vacuolar protein sorting homolog 35 (VPS35) and eukaryotic translation initiation factor 4 gamma 1 (EIF4G1), have been recently reported as causal in autosomal dominant Parkinson's disease (PD) among Caucasians. Their contribution to PD in other ethnic groups remains limited with 1% of VPS35 mutations observed in Caucasian and Japanese populations, but none in Chinese, and 11.57% of EIF4G1 mutations in Caucasian families and 0.09% and 0.17% in Caucasian and Chinese sporadic cases, respectively. We investigated the contribution, if any, of these 2 genes to familial and sporadic PD among the ethnically distinct Indian population. Complete exonic regions of these 2 genes were resequenced in 15 well-characterized PD families; the reported p.Asp620Asn in VPS35 and p.Arg1205His in EIF4G1 mutations were screened in an additional 54 familial and 251 sporadic PD cases, and no mutations were observed. These results, together with our previous reports on the absence of mutations in SNCA and LRRK2, warrant a continuing search for novel causative genes for PD among Indians.     

A novel presenilin 1 mutation (Ser169del) in a Chinese family with early-onset Alzheimer's disease

Early-onset familial Alzheimer's disease (EOFAD) has been associated with mutations in three genes, of which presenilin 1 (PSEN1) mutations are the most frequent. Here we report a novel PSEN1 mutation in a Chinese family with autosomal dominant Alzheimer's disease with an onset age in the early 40s. Molecular genetic analysis showed a 507-509delATC mutation at codon 169, leading to the deletion of serine in residue 169 (Ser169del). The amnestic presentation and absence of other features contrast with the other two mutations at codon 169 which have been associated with myoclonic jerks and seizures.     

Phactr2 and Parkinson's disease

Attempts at replicating the first genome-wide association study (GWAS) in Parkinson's disease (PD) have not successfully identified genetic risk factors. The present study reevaluates data from the first GWAS and focuses on the SNP (rs11155313, located in the Phactr2 gene) with the lowest P-value in the Tier 2 patient-control series. We employed four case-control series to examine the nominated SNP rs11155313 and identified association in US (OR: 1.39, P = 0.032), Canadian (OR: 1.41, P = 0.014) and Irish (OR: 1.44, P = 0.034) patient-control series, but not in the Norwegian series (OR: 1.15, P = 0.27). When combining all four series the observed trend was statistically significant (OR: 1.30, P < 0.001). This study shows that reappraisal of publicly available results of GWAS may help nominate new risk factors for PD.