亨廷顿病的发病机制和治疗进展

亨廷顿病（HD）为遗传性进行性神经变性疾病,以异常的自主运动、认知功能障碍和精神疾病为临床特征,中老年发病,发病后10～15年死亡。已知致病基因为IT15基因,其1号外显子含有一段多态性三核苷酸[胞嘧啶．腺嘌呤．鸟嘌呤（CAG）]重复序列,当CAG重复拷贝数大于36次即引起发病。     

亨廷顿病的分子发病机制及治疗进展

亨廷顿病(HD)又称慢性进行性舞蹈病,是以基底节区和大脑皮质变性为特征的常染色体显性遗传性疾病.多发生于中老年人,偶见于儿童和青少 年,男女均可患病,发病隐匿,呈缓慢进行性加重,平均生存期10～20年.临床主要表现为舞蹈样不自主动作、精神障碍和进行性痴呆,称为"三联征".     

亨廷顿病基因治疗研究进展

亨廷顿病是一种以运动、认知和精神障碍为主要表现的遗传性中枢神经系统变性疾病,其致病基因IT15突变可引起胞嘧啶腺嘌呤鸟嘌呤(CAG)三核苷酸重复序列异常扩增,导致所编码的亨廷顿蛋白构象变化并产生神经毒性作用。亨廷顿病的基因治疗目前尚处于临床前阶段,主要包括基因沉默、诱导突变亨廷顿蛋白清除、导入神经营养因子基因,以及纠正突变型亨廷顿蛋白的毒性作用所致的基因转录、信号转导和线粒体代谢紊乱等。本文尝试对亨廷顿病的基因治疗研究进展简要叙述。     

原发性震颤的发病机制及治疗进展

原发性震颤(ET)是较为常见的神经系统疾病之一,有30%～50%患者被误诊为帕金森病或其他震颤性疾病.传统观点认为,原发性震颤是良性、家族性、单一症状性疾病,以上肢的姿势性或动作性震颤为主要特征.随着相关研究的深入,学术界对这一观点提出了质疑.     

亨廷顿病发病机制的研究进展

亨廷顿病是由于IT15基因突变而产生,其导致huntingtin蛋白(Htt)的N端大量多聚谷氨酰胺重复扩张。重复扩张的多聚谷氨酰胺持续改变着正常Htt功能。并且这种变异的蛋白(Htt)本身是有毒性的。本文从Htt在神经元中不能够被泛素蛋白酶体系统所溶解的异常聚集、神经元基因转录水平失调导致显性改变、神经元线粒体和新陈代谢的异常导致能量代谢水平下调、轴突传输改变和突触失衡等角度阐述了其发病机制的研究进展。     

IT15基因△2642多态性与亨廷顿病发病年龄的相关性

目的 探讨IT15基因△2642多态性位点的基因型对亨廷顿病(Huntington disease,HD)发病年龄的影响.方法 采用聚合酶链反应-限制性片段长度多态性(PCR-RFLP)结合聚丙烯酰胺凝胶电泳(PAGE)技术及银染法,检测29例已行基因诊断的HD患者和38名健康对照者的IT15基因△2642多态性位点基因型,比较2组间△2642基因型分布,分析△2642基因型与HD发病年龄之间的关系.结果 两组均未检测到B/B基因型.△2642基因型A/A和A/B在HD组分布频率分别为65.5%和34.5%,在对照组分布频率分别为92.1%和7.9%(x2=7.435,P=0.006).等位基因B在HD患者的频率分布高于对照组(分别为17.2%、3.9%,OR=5.07,95%(7I 147～15.12,P=0.010).A/B型和A/A型HD患者CAG重复次数差异无统计学意义(P=0.188).HD组中基因型AVB患者发病年龄[(37.33±6.46)岁]较基因型A/A患者[(47.10±10.86)岁]早,差异有统计学意义(t=2.491,P=0.019).结论 IT15基因△2642基因型可能影响HD发病年龄,基因型A/B患者的发病年龄较基因型A/A患者提前.     

亨廷顿病发病新说

野生型亨廷丁减少,可能是亨廷顿病发病原因之一.     

亨廷顿病发病新说

野生型亨廷丁减少，可能是亨廷顿病发病原因之一。     

少年型亨廷顿病临床与基因突变分析

研究背景亨廷顿病是一种常染色体显性遗传性神经系统退行性疾病.临床主要表现为舞蹈样动作、进行性认知功能减退及精神症状,神经影像学检查显示尾状核和大脑皮质萎缩.其致病基因IT15定位于4p16.3,由67个外显子组成编码亨廷顿蛋白,在其第1个外显子内存在一段多态胞嘧啶.腺嘌呤-鸟嘌呤(CAG)三核苷酸重复序列,正常范围为6～35次、异常36～250次.亨廷顿病多于成年期发病,具有外显不完全和延迟外显现象,而青少年型亨廷顿病临床较为少见.本研究针对一例少年期发病的亨廷顿病患者临床表型及其家系IT15基因CAG重复动态突变特征进行细致分析.方法 采用聚合酶链反应结合荧光标记毛细管电泳片段分析方法,对115例临床拟诊为亨廷顿病家系的先证者进行IT15基因CAG重复次数分析,经pMD18-T载体克隆测序验证部分阳性或携带中间重复等位基凶的样本.结果 经基因分析共发现109例患者携带异常扩展的IT15基因CAG重复序列,其中一例为少年期发病患者,临床以认知功能障碍和运动功能减退为首发症状,其父母临床表型正常.基因片段分析显示,患者IT15基因CAG重复次数为15/68次;其父母分别为17/37次和15117次.结论 (1)少年期发病的亨廷顿病与成年型临床表型不同,后者临床表现以舞蹈样运动、智能减退和精神异常为主,而少年型患者大多以认知功能障碍发病.(2)IT15基因扩展CAG重复序列在代问传递过程中会出现动态突变.引起发病年龄逐代提前,症状加重,即遗传早现.该家系患者之父携带中间等位基因37次重复,遗传给患者成为68次重复.在代间传递过程中发生了大幅度扩展,使CAG三核苷酸重复次数增加了31次,提示重复序列在父系遗传更不稳定.     

青少年型亨廷顿病10例临床表型及基因突变分析

目的总结青少年型亨廷顿病患者临床表型及IT15基因胞嘧啶-腺嘌呤-鸟嘌呤(CAG)重复突变特点。方法采用聚合酶链反应结合荧光标记毛细管电泳片段分析方法,对159个亨廷顿病家系272名成员进行IT15基因CAG重复序列检测,并对其中10例青少年期发病患者的临床表现、影像学特征以及临床表型与基因型相关性进行分析。结果经基因检测共发现211例携带异常扩展的IT15基因CAG重复序列,其中10例为青少年型亨廷顿病患者,临床表现各异,主要以不自主运动和认知功能障碍为主;发病年龄平均(12.50±4.55)岁,IT15基因CAG重复序列平均(63.70±14.83)个,Pearson相关分析显示,二者呈负相关关系(r=-0.865,P=0.001)。结论青少年型亨廷顿病与成年型亨廷顿病患者临床表现不同,前者主要表现为认知功能障碍;对于无明确家族史、临床表现疑似亨廷顿病的患者,基因检测是明确诊断的依据;亨廷顿病发病年龄与IT15基因CAG重复次数呈负相关,但不能完全解释发病年龄的变异性,尤以青少年型亨廷顿病患者显著,可能存在其他遗传调节因素。     

Recent advances in Huntington's disease

Huntington's disease is a progressive and fatal neurological disorder caused by the expansion of a CAG trinucleotide repeat in exon 1 of the gene coding for a protein of unknown function that has been named huntingtin. The exact cause of neuronal death in Huntington's disease is unknown; however, the leading hypothesis is that of excitotoxicity and apoptosis induced by a defect in energy metabolism that may be caused by oxidative stress. How mutant huntingtin might cause these processes is unknown. New animal and cell models provide insights into the mechanism of pathogenesis and the search for the development of effective therapies.     

Pathological mechanisms and therapeutic strategies for Alzheimer's disease

Alzheimer's disease is a rather complex neurodegenerative disease,which is attributed to a combination of multiple factors.Among the many pathological pathways,synaptic dysfunctions,such as synapses loss and deficits in synaptic plasticity,were thought to be strongly associated with cognitive decline.The deficiencies in various sorts of neurotransmissions are responsible for the multifarious neurodegenerative symptoms in Alzheimer's disease,for example,the cholinergic and glutamatergic deficits for cognitive decline,the excitatory and inhibitory neurotransmission dyshomeostasis for synaptic plasticity deficits and epileptiform symptoms,and the monoamine neurotransmission for neuropsychiatric symptoms.Amyloid cascade hypothesis is the most popular pathological theory to explain Alzheimer's disease pathogenesis and attracts considerable attention.Multiple lines of genetic and pathological evidence support the predominant role of amyloid beta in Alzheimer's disease pathology.Neurofibrillary tangles assembled by microtubule-associated protein tau are other important histopathological characteristics in Alzheimer's disease brains.Cascade of tau toxicity was proved to lead to neuron damage,neuroinflammation and oxidative stress in brain.Ageing is the main risk factor of neurodegenerative diseases,and is associated with inflammation,oxidative stress,reduced metabolism,endocrine insufficiencies and organ failures.These aging related risk factors were also proved to be some of the risk factors contributing to Alzheimer's disease.In Alzheimer's disease drug development,many good therapeutic strategies have been investigated in clinical evaluations.However,complex mechanism of Alzheimer's disease and the interplay among different pathological factors call for the come out of allpowerful therapies with multiple curing functions.This review seeks to summarize some of the representative treatments targeting different pathological pathways currently under clinical evaluations.Multi-target therapies as an emerging strategy for Alzheimer's disease treatment will be highlighted.     

Screening of therapeutic strategies for Huntington's disease in YAC128 transgenic mice

Huntington’s disease (HD) is a hereditary neurodegenerative disorder caused by an unstable expansion of cytosine-adenine-guanine (CAG) repeats in the HD gene. The symptoms include cognitive dysfunction and severe motor impairment with loss of voluntary movement coordination that is later replaced by bradykinesia and rigidity. The neuropathology is characterized by neuronal loss mainly in the striatum and cortex, and the appearance of neuronal intranuclear inclusions of mutant huntingtin. The mechanisms responsible for neurodegeneration are still not fully understood although excitotoxicity and a consequent increase in intracellular calcium concentration as well as the activation of caspases and calapins are known to play a key role. There is currently no satisfactory treatment or cure for this disease. The YAC128 transgenic mice express the full-length human HD gene with 128 CAG repeats and constitute a unique model for the study of HD as they replicate the slow and biphasic progression of behavioral deficits characteristic of the human condition and show striatal neuronal loss. As such, these transgenic mice have been an invaluable model not only for the elucidation of the neurodegenerative pathways in HD, but also for the screening and development of new therapeutic approaches. Here, I will review the unique characteristics of this transgenic HD model and will provide a summary of the therapies that have been tested in these mice, namely: potentiation of the protective roles of wild-type huntingtin and mutant huntingtin aggregation, transglutaminase inhibition, inhibition of glutamate- and dopamine-induced toxicity, apoptosis inhibition, use of essential fatty acids, and the novel approach of intrabody gene therapy. The insights obtained from these and future studies will help identify potential candidates for clinical trials and will ultimately contribute to the discovery of a successful treatment for this devastating neurodegenerative disorder.     

Clinical and research advances in Huntington's disease

Huntington's disease (HD) is an autosomal dominant neurodegenerative disorder characterized by abnormalities of movement and dementia. No curative treatment is available and HD results in gradually increasing disability. Characterization of the genetic abnormality has dramatically increased our understanding of the underlying mechanisms of the disease process, and has resulted in the development of a number of genetic models. These research tools are forming the basis of advanced work into the diagnosis, pathophysiology, and potential treatment of the disease. Clinically, the availability of genetic testing has eased confirmation of diagnosis in symptomatic individuals. Presymptomatic testing allows at-risk individuals to make informed choices but requires supportive care from physicians. Current clinical treatment is focused on symptom control. Advances in research have resulted in the development of potential neuroprotective strategies which are undergoing clinical testing.     

Altered microRNA expression in animal models of Huntington’s disease and potential therapeutic strategies

A review of recent animal models of Huntington’s disease showed many microRNAs had altered expression levels in the striatum and cerebral cortex,and which were mostly downregulated.Among the altered microRNAs were miR-9/9*,miR-29b,miR-124a,miR-132,miR-128,miR-139,miR-122,miR-138,miR-23b,miR-135b,miR-181(all downregulated)and miR-448(upregulated),and similar changes had been previously found in Huntington’s disease patients.In the animal cell studies,the altered microRNAs included miR-9,miR-9*,miR-135b,miR-222(all downregulated)and miR-214(upregulated).In the animal models,overexpression of miR-155 and miR-196a caused a decrease in mutant huntingtin mRNA and protein level,lowered the mutant huntingtin aggregates in striatum and cortex,and improved performance in behavioral tests.Improved performance in behavioral tests also occurred with overexpression of miR-132 and miR-124.In the animal cell models,overexpression of miR-22 increased the viability of rat primary cortical and striatal neurons infected with mutant huntingtin and decreased huntingtin-enriched foci of≥2μm.Also,overexpression of miR-22 enhanced the survival of rat primary striatal neurons treated with 3-nitropropionic acid.Exogenous expression of miR-214,miR-146a,miR-150,and miR-125b decreased endogenous expression of huntingtin mRNA and protein in HdhQ111/HdhQ111 cells.Further studies with animal models of Huntington’s disease are warranted to validate these findings and identify specific microRNAs whose overexpression inhibits the production of mutant huntingtin protein and other harmful processes and may provide a more effective means of treating Huntington’s disease in patients and slowing its progression.     

Recent advances on the pathogenesis of Huntington's disease

We review recent advances regarding the pathogenesis of Huntington's disease (HD). This genetic neurodegenerative disorder is caused by an expanded CAG repeat in a gene coding for a protein, with unknown function, called huntingtin. There is selective death of striatal and cortical neurons. Both in patients and a transgenic mouse model of the disease, neuronal intranuclear inclusions, immunoreactive for huntingtin and ubiquitin, develop. Huntingtin interacts with the proteins GAPDH, HAP-1, HIP1, HIP2, and calmodulin, and a mutant huntingtin is specifically cleaved by the proapoptotic enzyme caspase 3. The pathogenetic mechanism is not known, but it is presumed that there is a toxic gain of function of the mutant huntingtin. Circumstantial evidence suggests that excitotoxicity, oxidative stress, impaired energy metabolism, and apoptosis play a role.     

Huntington's disease: Current and future therapeutic prospects

Huntington's disease is a progressive neurodegenerative disorder for which therapies are woefully inadequate and do not prevent inevitable progression. Currently approved therapies are primarily aimed at treating chorea, but do not address the more clinically meaningful motor, behavioral, and cognitive features of the disease. However, there are a number of promising new therapies that are currently being studied in the laboratory, and in the clinic. This article will review the wide variety of therapies currently being tested, the advances in clinical trials and end points, and the many potentially relevant new targets. © 2018 International Parkinson and Movement Disorder Society     

Recent advances in understanding the pathogenesis of Huntington's disease.

Huntington's disease (HD) is an autosomal, dominantly inherited neurodegenerative disorder that is characterized by abnormal involuntary movements (chorea), intellectual impairment and selective neuronal loss. The expansion of a polymorphic trinucleotide repeat (the sequence CAG that codes for glutamine) to a length that exceeds 40 repeat units in exon 1 of the gene, HD, correlates with the onset and progression of the disease. The protein encoded by HD, huntingtin, is normally localized in the cytoplasm, whereas the mutant protein is also found in the nucleus, suggesting that its translocation to this site is important for the pathogenesis of HD. Although several proteins that interact with huntingtin have been identified in vitro, the significance of these interactions with the mutant protein in the pathogenesis of HD has yet to be determined. Recent progress in the development of cellular and animal models for the disease have provided invaluable insights and resources for studying the disease mechanisms underlying HD, and will be useful for screening and evaluating possible therapeutic strategies.     

Promises and pitfalls of immune-based strategies for Huntington's disease

Huntington's disease (HD) is an autosomal-dominant neurodegenerative disease characterized by the selec-tive loss of neurons in the striatum and cortex, leading to progressive motor dysfunction, cognitive decline and behavioral symptoms. HD is caused by a trinucleotide (CAG) repeat expansion in the gene encoding for huntingtin. Several studies have suggested that inflammation is an important feature of HD and it is already observed in the early stages of the disease. Recently, new molecules presenting anti-inflammatory and/or immunomodulatory have been investigated for HD. The objective of this review is to discuss the data obtained so far on the immune-based therapeutic strategies for HD.