Shu-yu Zhang

CHCHD2 gene mutations in familial and sporadic Parkinson's disease

Mutations in CHCHD2 gene have been reported in autosomal dominant Parkinsons disease (ADPD). However, there is still lack of evidence supported CHCHD2 mutations lead to ADPD in other populations. We performed whole exome sequencing, positron emission tomography (PET), and haplotype analyses in an ADPD pedigree and then comprehensively screened for CHCHD2 gene mutations in additional 18 familial parkinsonism pedigrees, 364 sporadic PD patients, and 384 healthy controls to assess the frequencies of known and novel rare nonsynonymous CHCHD2 mutations. We identified a heterozygous variant (c.182C>T; p.Thr61Ile) in the CHCHD2 gene in the ADPD pedigree. PET revealed a significant reduction in dopamine transporter binding in the putamen and caudate nucleus of the proband, similar to idiopathic PD. The single nucleotide variant 5C>T (Pro2Leu) in CHCHD2 was confirmed to have a significantly higher frequency among sporadic PD patients than controls. Our results confirm that ADPD can be caused by CHCHD2 mutations and show that the Pro2Leu variant in CHCHD2 may be a risk factor for sporadic PD in Chinese populations.

A novel RAB39B gene mutation in X-linked juvenile parkinsonism with basal ganglia calcification.

Mutations in RAB39B have been reported as a potential cause of X‐linked Parkinsons disease (PD), a rare form of familial PD. We conducted a genetic analysis on RAB39B to evaluate whether RAB39B mutations are related to PD in the Chinese population.

MC1R variants in Chinese Han patients with sporadic Parkinson's disease

Recently, a variant p.R160W in the MC1R gene was identified that increased the risk of Parkinsons disease (PD) in Spanish population. To explore whether the MC1R gene variants are associated with sporadic PD in Chinese population, we performed a case-control comparison study for comprehensive MC1R variant screening in 510 Chinese Han patients and 495 healthy controls as ethnically matched controls. We identify 5 nonsynonymous variants, including rs34090186 (p.R67Q), rs2228479 (p.V92M), rs33932559 (p.I120T), rs885479 (p.R163Q), and rs372152373 (p.R223W). However, variants mentioned previously did not show association with PD. Our results suggest that variants in MC1R do not play a major role in PD in the Chinese population.

Genetic analysis of the TMEM230 gene in Chinese Han patients with Parkinson’s disease

TMEM230 mutations have been recently reported to cause autosomal dominant Parkinson’s disease (PD). However, there are limited studies from different ethnic populations to support the role of TMEM230 in sporadic PD. In this study, we performed a comprehensive TMEM230 mutation screening in 550 sporadic PD patients and 560 controls to elaborate the genetic contribution of TMEM230 to sporadic PD. Overall, we did not find any pathogenic mutations in the coding sequence, while we identified four variants (c.68 + 182G > A, c.78A > G, c.552 + 11A > G and c.174 + 11C > T) both in the patients and controls, and c.68 + 182G > A appeared to be associated with an increased risk of PD (odds ratio 1.782, 95% confidence interval 1.035–3.067, p < 0.05). After Bonferroni correction, however, c. 68 + 182G > A had no significant association with sporadic PD (pc = 0.136, pc > 0.05). Thus our results suggest that TMEM230 gene mutations may be rare in Chinese populations, and the variability of TMEM230 gene may not be a main factor for sporadic PD patients in Chinese Han populations. More evidence is still needed to clarify this question.

DNAJC6 mutations are not common causes of early onset Parkinson’s disease in Chinese Han population

DNAJC6 has been reported as a causative gene for early onset Parkinsons disease (EOPD) in some populations, and different mutations have been reported to be associated with EOPD. However, Until now, there is limited information about DNAJC6 gene test in sporadic EOPD patients in Chinese population. Herein, we performed comprehensive DNAJC6 mutation screenings in 117 EOPD patients from Chinese population. None of the reported disease-causing mutations were found. However, we identified a novel non-synonymous heterozygous variant c.2798T>C (p.Val933Ala). Bioinformatics analysis demonstrate that the c.2798T>C variant exhibits highly conserved residues across species. Our data suggests that DNAJC6 mutations are not common causes of EOPD in Chinese population.

Brain glucose metabolism changes in Parkinson's disease patients with CHCHD2 mutation based on 18F-FDG PET imaging

The progress in functional neuroimaging has contributed to better understanding of neurodegenerative disease such as Parkinsons disease [1,2]. The application of glucose metabolism network analysis has led to the validation of a distinct spatial covariance patterns associated with the motor manifestations of the disease. Parkinsons diseaserelated pattern (PDRP) can potentially be used as a clinical biomarker in the early diagnosis and assessment of the treatment effect in Parkinsons disease. However, most of the previous studies are about sporadic Parkinsons disease, and few studies are conducted about hereditary Parkinsons disease. CHCHD2mutations have recently been identified in families with autosomal dominant Parkinsons disease (ADPD); these patients present with dopa-responsive parkinsonism [3]. We have identified the p.Thr61Ile in mutation in CHCHD2 in a Chinese family with ADPD (Fig. 1A) [4]. The proband (III-5) developed symptoms at age 48, including tremor and rigidity of the left arm. And the probands sister (III-4) manifested symptoms of mild tremor and stiffness affecting her right arm and slightly masked face at age 47. In addition, the probands other sibling (III-7) developed a slight tremor at age 39. Through PET scans, the proband (III-5) exhibited significant reductions in dopamine transporter (DAT) binding in the putamen and caudate nucleus similar to idiopathic PD. And the probands brother (III-7) also showed lower uptake ratios in the bilateral putamen, which may indicate a loss of presynaptic afferents in the putamen. The normal genotype family member (III-6) showed no DAT binding abnormalities (Fig. 1B, Table 1). These results implied that the probands brother (III-7) might be in a state before other parkinsonism symptoms. F-fluorodeoxyglucose (FDG) positron emission tomography (PET) scans were performed for III-5, III-6 and III-7. To characterize metabolic activity in the PD patients compared with controls, we performed a group comparison by using a two-sample t-test according to the general linear model at each voxel. The contrasts for the decreased and increased metabolism were set as [1 −1] and −1 1 1⁄2 . To evaluate significant differences, we set the peak threshold at P b 0.01 (uncorrected) overwhole brain regions. The SPMmaps for increased or decreasedmetabolism were overlaid on a standard T1-weighted MRI brain template

CHCHD10 is involved in the development of Parkinson’s disease caused by CHCHD2 loss-of-function mutation p.T61I

Previously we identified the p.Thr61Ile mutation in coiled-coil-helix-coiled-coil-helix domain containing 2 (CHCHD2) in a Chinese family with autosomal dominant Parkinsons disease. But the mechanism is still unclear. In this study, we explored the effects of CHCHD2 p.Thr61Ile mutation in cells and its association with coiled-coil-helix-coiled-coil-helix domain containing 10 (CHCHD10). We found that overexpression of Parkinsons disease-associated T61I mutant CHCHD2 did not produce mitochondrial dysfunction. Rather, its protective effect from stress was abrogated. And, the level of the CHCHD2 protein and mRNA in patient fibroblasts was not significantly different from control. In addition, CHCHD2 T61I mutation caused increased interaction with CHCHD10 and reduced CHCHD10 level. The mitochondrial ultrastructural alterations in CHCHD2 T61I mutant patient fibroblasts are similar to that of CHCHD10 mutations. We therefore propose that CHCHD10 is involved in the development of Parkinsons disease caused by CHCHD2 loss-of-function mutation p.T61I.

CADASIL mutant NOTCH3(R90C) decreases the viability of HS683 oligodendrocytes via apoptosis

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is the most common hereditary cerebral small vessel disease caused by mutations in NOTCH3. Prevailing models suggest that demyelination occurs secondary to vascular pathology. However, in zebrafish, NOTCH3 is also expressed in mature oligodendrocytes. Thus, we hypothesized that in addition to vascular defects, mutant NOTCH3 may alter glial function in individuals with CADASIL. The aim of this study was to characterize the direct effects of a mutant NOTCH3 protein in HS683 oligodendrocytes. HS683 oligodendrocytes transfected with wild-type NOTCH3, mutant NOTCH3(R90C), and empty control vector were used to study the impact of the NOTCH3(R90C) mutant on its protein hydrolytic processing, cell viability, apoptosis, autophagy, oxidative stress, and the related upstream events using immunoblotting, immunofluorescence, RT-PCR, and flow cytometry. We determined that HS683 oligodendrocytes transfected with mutant NOTCH3(R90C), which is the hotspot mutation site-associated with CADASIL, exhibited aberrant NOTCH3 proteolytic processing. Compared to cells overexpressing wild-type NOTCH3, cells overexpressing NOTCH3(R90C) were less viable and had a higher rate of apoptosis. Immunoblotting revealed that cells transfected with NOTCH3(R90C) had higher levels of intrinsic mitochondrial apoptosis, extrinsic death receptor path-related apoptosis, and autophagy compared with cells transfected with wild-type NOTCH3. This study suggests that in patients with CADASIL, early defects in glia influenced by NOTCH3(R90C) may directly contribute to white matter pathology in addition to secondary vascular defects. This study provides a potential therapeutic target for the future treatment of CADASIL.

Exome capture sequencing identifies a novel CCM1 mutation in a Chinese family with multiple cerebral cavernous malformations.

Purpose: Cerebral cavernous malformations (CCMs) are vascular anomalies predominantly in the central nervous system but may include lesions in other tissues, such as the retina, skin and liver. The main clinical manifestations include seizures, hemorrhage, recurrent headaches and focal neurological deficits. Previous studies of familial CCMs (FCCMs) have mainly reported in Hispanic and Caucasian cases. Here, we report on FCCMs in a Chinese family further characterized by a novel CCM1 gene mutation. Materials and methods: We investigated clinical and neuroradiological features of a Chinese family of 30 members. Furthermore, we used exome capture sequencing to identify the causing gene. The CCM1 mRNA expression level in three patients of the family and 10 wild-type healthy individuals were detected by real-time quantitative polymerase chain reaction (real-time RT-PCR). Results: Brain magnetic resonance imaging demonstrated multiple intracranial lesions in seven members. The clinical manifestation of CCM was found in five of these cases, including recurrent headaches, weakness, hemorrhage and seizures. Moreover, we identified a novel nonsense mutation c.1159G>T (p. E387*) in the CCM1 gene in the pedigree. Based on real-time RT-PCR results, we have found that the CCM1 mRNA expression level in three patients was reduced by 35% than that in wild-type healthy individuals. Conclusions: Our finding suggests that the novel nonsense mutation c.1159G>T in CCM1 gene is associated with FCCM, and that CCM1 haploinsufficiency may be the underlying mechanism of CCMs. Furthermore, it also demonstrates that exome capture sequencing is an efficient and direct diagnostic tool to identify causes of genetically heterogeneous diseases.

Plasma Homocysteine, Vitamin B12 and Folate Levels in Multiple System Atrophy: A Case-Control Study

Background Multiple system atrophy (MSA) is a neurodegenerative disease, and its pathological hallmark is the accumulation of α-synuclein proteins. Homocysteine (Hcy) is an intermediate amino acid generated during the metabolism of methionine. Hcy may contribute to the pathogenesis of neurodegenerative disorders. Vitamin B12 and folate are cofactors necessary for the methylation of homocysteine. Methods This study compared the levels of serum Hcy, vitamin B12 and folate in patients with MSA with those in healthy people to reveal the possible association between MSA and plasma levels of Hcy, vitamin B12 and folate. We enrolled 161 patients with MSA and 161 healthy people in this study. The association between MSA and the levels of Hcy, vitamin B12 and folate were analyzed using binary logistic regression. Results The mean level of Hcy in patients with MSA was significantly higher than that in healthy controls (16.23 ± 8.09 umol/l vs 14.04 ± 4.25 umol/l, p < 0.05). After adjusting for age, sex and medical history, the odds ratio for Hcy was 1.07 (95% CI = 1.01–1.13, p < 0.05) for patients with MSA. Vitamin B12 and folate levels were not significantly different between patients with MSA and controls. Conclusion Our data suggest that higher levels of Hcy may be associated with an increased risk for MSA.