(10)认知症的遗传风险-Genetic risk for dementia-公开课-关爱惟士
(10)认知症的遗传风险-Genetic risk for dementia

http://player.youku.com/embed/XMjY3ODMzMjY0OA



Dr Blochs

Blochs博士


Hello and welcome to the Wicking Dementia Laboratory, where one of the things we are working to understand is the genetics of dementia. When someone in their family has dementia, people are naturally concerned about whether it can be inherited. The genetics of dementia is complex and not fully understood. However, we do know that the vast majority of cases of dementia is not caused by an inherited genetic mutation. Dementia is so common that having several close relatives with dementia is not evidence of a genetic link.

您好,欢迎来到Wicking认知症实验室,我们正在此为搞清痴呆遗传学而工作。当他们的家族中有人患有认知症时,人们自然会关心是否这种疾病是否会遗传。痴呆遗传学是复杂的和未被充分了解的。然而我们知道绝大多数认知症的病例不是由遗传性基因突变引起的。认知症是如此常见,以至于有若干近亲患认知症不是遗传链接的证据。


There are a few gene mutations we know about that do cause dementia, however. So for a very small number of families, dementia can be inherited when the mutation is passed on. In these rare genetic forms of dementia, the onset is usually at a younger age, in the 40s or 50s.

但是据我们所知,有一些基因突变会导致认知症。因此对于非常少数的家族,当突变传递时,认知症可以被遗传。在这些罕见的认知症遗传形式中,人们通常会在40或50岁左右比较年轻的年龄发病。


Let’s meet one of those families. This is the Appleton family.

让我们会见其中的一个家庭。这是阿普尔顿家族。


This is Alan Appleton, and he has familial Alzheimer’s disease. He inherited a faulty gene that causes Alzheimer’s from his mother, who also had the disease.

这是阿兰·阿普尔顿,他有家族性阿尔茨海默病。他从他的母亲那里遗传了一个导致阿尔茨海默病的错误的基因,他的母亲也有这种疾病。


Three genes have been identified which, if mutated in certain ways, will cause familial Alzheimer’s disease. The mutation causing Alan’s Alzheimer’s is in a gene called APP.

已有三种基因被鉴定,如果它们以某些方式突变,将引起家族性阿尔茨海默病。导致Alan的阿尔茨海默症的突变存在称为APP的基因中。


We inherit half our genes from our mother and half from our father. While Alan inherited a faulty copy of the APP gene from his mother, he also inherited a normal copy from his father.

我们从自己的母亲继承了一半的基因,从自己的父亲继承了另一半的基因。虽然艾伦从他的母亲那里继承了一个有错误的APP基因拷贝,但他也继承了他父亲的正常基因拷贝。


This is Alice, Alan’s partner. Her mother also had Alzheimer’s disease, but it was the common sporadic type, so Alice has two normal copies of the APP gene.

这是爱丽丝,她是阿兰的配偶。她的母亲也有阿尔茨海默病,但它是常见的多发类型,所以爱丽丝有两个正常的APP基因拷贝。


Meet April and Augustus, Allan and Alice’s children. When someone carries a faulty gene that causes dementia, there is a 50-50 chance they will pass it on to their child, because they could pass on either their faulty or normal copy of the gene.

再来看艾伦和爱丽丝的孩子April和Augustus。当他们携带导致认知症的错误基因时,他们有一半的机会将它传递给他们的孩子,因为他们可以传递他们的错误或正常的基因拷贝。


April inherited the normal APP gene from her father and from her mother, so she will not get familial Alzheimer’s disease. She could still get sporadic Alzheimer’s disease, but she is at no greater risk than anyone else in the population.

April从她的父亲和母亲那里遗传了正常的APP基因拷贝,所以她不会得家族性阿尔茨海默病。她仍然可以患多发性的阿尔茨海默病,但她没有比人口中的任何人更大的风险。


Augustus on the other hand, inherited the faulty APP gene from his father and a normal gene from his mother. He will develop familial Alzheimer’s disease because the mutated gene is dominant over the normal copy.

在另一方面,奥古斯遗传了他父亲的错误APP基因拷贝和他母亲的正常基因拷贝。他将发展家族性阿尔茨海默病,因为突变基因拷贝比正常基因拷贝占优势。


Genetic forms of Alzheimer’s disease like the one affecting Alan and Augustus Appleton account for only around 1% of cases. So the vast majority of cases are sporadic, which means their cause is unknown. There are also other gene mutations that can cause other types of dementia, but for all the common causes of dementia, most cases are not inherited.

像艾伦和Augustus的这样的遗传性阿尔茨海默病,大约只占1%的病例。所以绝大多数情况是多发性的,这意味着他们的病因是未知的。还有其他可导致其他类型认知症的基因突变,但对于认知症的所有常见病因,大多数不是遗传性的。


So what about the sporadic forms of dementia, do genes play a role there? Research shows that, on average, people who have a close relative with a sporadic form of dementia have an increased risk of developing the condition, compared to someone without that family history. The increase in risk is similar to the increase we see for other risk factors like diabetes or smoking. And it is likely due to a combination of genetic and environmental influences on our risk of dementia.

那么对于多发性类型的认知症,基因是否在那里发挥作用呢?研究表明,平均来说,与没有家族史的人相比,具有患多发性认知症的近亲的人具有更高的发展该病症的风险。风险的增加类似于我们看到的像糖尿病或吸烟等其他风险因素导致的增加。这可能是由于遗传和环境共同影响我们患认知症的风险的缘故。


One of the genetic influences on our risk of Alzheimer’s disease is a gene called APOE. This gene comes in three normal variations. APOE3 is the most common variation, and doesn’t influence our risk of Alzheimer’s disease. APOE2 is associated with reduced risk, while APOE4 is known to increase the risk.

对我们患阿尔茨海默病的风险的遗传影响之一是称为APOE的基因。这个基因有三种常见的变异类型。 APOE3是最常见的变异,并不影响我们患阿尔茨海默病的风险。 APOE2与降低的风险相关,而APOE4已知会增加风险。


APOE4 does not cause Alzheimer’s, it only increases the risk of it developing. Some people with APOE4 never develop Alzheimer’s disease, and others who develop Alzheimer’s do not have APOE4. So even if someone has the APOE4 gene, it is impossible to predict whether or not they will develop dementia, but they are at increased risk.

APOE4不会引起阿尔茨海默症,它只会增加发展该病的风险。一些有APOE4基因的人从未发展成阿尔茨海默病,而发展成阿尔茨海默病的人没有APOE4。因此,即使有人拥有APOE4基因,也不可能预测他们是否会发展为认知症,但他们的患病风险有所增加。


In addition to APOE4, many other genes have been identified that have smaller effects on the risk of dementia. We are each born with an individual mix of genes, some of which may reduce our risk of dementia while others may increase it. At this time, it is not possible to measure any person’s individual genetic risk for dementia.

除了APOE4,许多其他基因已被确定对痴呆的风险有较小的影响。我们每个人都在出生时,带着各自的基因混合,其中一些基因可能会降低我们患认知症的风险,而其它的基因会增加风险。因此测量任何一个人的患认知症的个体遗传风险是不可能的。


Thanks for visiting the Wicking Dementia Laboratory and I hope you’ve enjoyed learning about the genetics of dementia.

感谢您访问Wicking认知症实验室,我希望您喜欢学习认知症的遗传学。

翻译:关爱惟士-未经允许不得转载,违者必追究法律责任


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