晚发型帕金森病是最常见的类型,其患病风险会随着年龄增长而提高。随着人类寿命的延长,预计未来几十年帕金森病患者的数量将持续增加。
DA metabolism in dopaminergic neurons. In addition to the uptake of dopamine (DA) by the DA transporter (DAT) from outside, Dopaminergic neurons produce DA under the action of tyrosine hydroxylase (TH) and aromatic amino acid decarboxylase (AADC). The newly synthesized or taken up DA is stored in vesicles with the aid of vesicular monoaminergic transporter-2 (VAMT2). Cytosolic DA can be degraded in neurons or glial cells by catechol-o-methyltransferase (COMT) or monoamine oxidase (MAO) to form homovanillic acid (HVA) or be oxidized to form the metabolites (DOPAL, and DOPAC) and hydrogen peroxide (H2O2).
Genetic architecture of Parkinson's disease.
Continuum of genetic variants of different severity and frequency. The size of each bubble corresponds to the approximate population frequency of each allele. Colours indicate the form of inheritance: dominant (red), recessive (yellow), and risk loci (green). Genetic risk factors for PD can be divided into 3 groups.
Group A includes the majority of Mendelian genes associated with PD. These variants are associated with a significant risk of PD, but are very rare.
Group B includes more frequent variants that are associated with moderately high risk of PD. This group currently includes GBA1 and LRRK2 variants.
Group C includes variants associated with low risk of PD, but which are observed in a high percentage of patients with the disease.
This group includes over 90 potential independent genome-wide significant signals detected in a genome-wide association study meta-analysis of over 13 000 patients and 95 000 controls. Like LRRK2 and SNCA, some VPS13C and GCH-1 mutations are probably causal or associated with high risk of PD.
相反,如果涉及PARK2、PARK7或PINK1基因,疾病通常表现为常染色体隐性遗传,这需要两个基因拷贝均发生突变才能引发疾病。这意味着患者从父母双方分别遗传了突变基因,但父母本身可能没有任何帕金森病的症状。
SNCA(alpha-synuclein gene):SNCA基因负责生成α-突触核蛋白。在帕金森病患者的脑细胞中,这种蛋白质聚集在称为路易体(Lewy bodies)的团块中。该基因的突变或重复可能导致蛋白质异常积聚,从而损害神经元功能,是最早发现与帕金森病相关的基因之一。SNCA基因突变发生在早发性帕金森病中。
LRRK2(Leucine rich-repeat kinase 2):由LRRK2产生的蛋白质是一种蛋白激酶。该基因的突变是导致家族性和散发性帕金森病最常见的原因之一。
PINK1(PTEN-induced kinase 1):PINK 1产生的蛋白质也是一种蛋白激酶,可以保护线粒体免受压力。PINK 1突变发生在早发性帕金森病中。
PRKN(PARK2):编码 Parkin蛋白,这是一种 E3 泛素蛋白连接酶,对蛋白质泛素化和受损线粒体的有丝分裂非常重要。该基因的突变可引发早发型帕金森病,影响蛋白质降解通路。
PARK7:这种基因的突变会导致一种罕见的早发性帕金森病。PARK 7基因产生蛋白质DJ-1,该蛋白质可保护线粒体免受压力。
GBA:基因(1q21)编码葡萄糖脑苷脂酶(glucocerebrosidase)(也称为葡萄糖神经酰胺酶,glucosylceramidase),一种参与鞘脂代谢的溶酶体酶。其功能是催化膜脂葡萄糖神经酰胺水解为神经酰胺和葡萄糖。神经酰胺是鞘糖脂的前体(如GM1、GM2和GM3神经节苷脂)和鞘磷脂。GBA基因是戈谢病(Gaucher disease, GD)的致病基因,其变异不仅会导致GD,还可能是帕金森病(PD)的风险因素。部分GD患者的家族成员常携带单等位基因GBA1变异,提示其与PD的发病风险相关。常见的与PD相关的GBA1变异包括p.E326K、p.T369M、p.N370S和p.L444P,这些变异会降低GBA1编码的葡萄糖脑苷脂酶活性,削弱溶酶体对α-突触核蛋白的降解能力。GBA1变异的频率在不同种族中有所差异,例如p.E326K在欧洲人中较常见,但在亚洲非常罕见。
etc.
帕金森病遗传因素研究的策略及应用
研究帕金森病的遗传因素主要依赖于对患者的分子遗传特征分析,并将样本分为家族性帕金森病和散发性帕金森病两组。这种分类方法有助于识别特定的致病基因。
在发现与帕金森病相关的基因后,研究人员利用细胞和动物模型进一步探讨这些基因在疾病中的病理生理作用。这些模型为理解帕金森病的发病机制提供了重要线索,同时为开发精准医学应用(如基因疗法或靶向治疗)奠定了基础。
结语
帕金森病的遗传学研究不仅揭示了疾病的发生机制,还为精准医疗和个性化治疗开辟了新的方向。从基因检测到靶向治疗,这些进展为患者带来了希望,也为研究人员和临床医生提供了新的工具。未来,随着遗传学与临床实践的进一步融合,有望实现帕金森病的更早诊断、更精准治疗和更有效预防。
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