Investigating the influence of genetic variation associated with age-related macular degeneration on plasma levels of complement regulatory proteins

老年性黄斑变性（AMD）是西方世界致盲的主要原因。最近，已经很清楚，一个人的基因组成对他们患AMD的风险有很大的影响。已经发现了具有“保护性”的基因变异，即具有这些变异的个体患AMD的风险较低，而具有“致病性”的基因变异，即它们的存在会导致风险增加。有两个主要的基因区域可以改变AMD的风险。其中一个位于第10号染色体上，人们对它知之甚少。另一个位于1号染色体上，提供了一系列蛋白质的编码，这些蛋白质被称为补体因子H （FH）、因子H样蛋白1 （FHL-1）和5种称为因子H相关1-5 （FHR1-5）的蛋白质。这些蛋白质参与调节免疫系统中称为补体级联的部分。人们认为，1号染色体上的遗传变异改变了这些蛋白质的数量，导致眼睛发炎，最终导致黄斑变性。这得到了许多研究的支持，这些研究表明，这些蛋白质中的一种缺失或其序列（因此功能）的改变可以改变AMD发生的风险。虽然假设这些amd相关的遗传变异改变了体内FH、FHL1和FHR1-5的水平，但这一点很难得到证实。这些蛋白质非常相似（事实上，FHL-1与FH的前半部分完全相同，除了一端有一个非常小的标签）。这意味着基于形状识别和测量蛋白质的标准方法充满了问题，因为很难准确证明被测量的是哪种形状。在这个项目中，我们将采用一种不同的方法-质谱（MS）。质谱的工作原理是“称量”感兴趣的分子，然后计算每种分子的数量。既然我们知道这些蛋白质的结构，我们就可以计算出它们的质量，并以非常高的信心检测它们。事实上，作为常规临床护理的一部分，MS现在被常规用于检测许多化合物的血液水平。我们开发了一种基于质谱的方法，可以同时测量血浆中所有七种感兴趣的蛋白质的水平。这种方法很有价值。我们将用它来分析我们已经使用标准方法的血液样本，看看结果如何匹配，显示哪些方法是可靠的。其次，我们将测量这7种蛋白在作为AMD大型遗传研究的一部分收集的血浆中的水平。这些血液样本的捐献者已经确定了他们的基因图谱。通过测量蛋白质的数量，我们可以与基因数据进行比较，并首次看到基因如何影响每种蛋白质的水平，以及这些蛋白质的水平如何导致AMD的风险。这项研究将为AMD的发展提供新的认识，将提高我们定义风险的能力，并可能允许开发或监测新的治疗方法。这种检测方法对其他疾病的研究也很有用。已知这些蛋白质对某些肾脏疾病很重要，可靠的测量方法对研究和临床护理都很重要。也有证据表明，它们会导致阿尔茨海默病等其他疾病。

Age-related Macular Degeneration (AMD) is the leading cause of blindness in the Western world. Recently, it has become clear that the genetic make-up of an individual has a strong influence on their risk of developing AMD. Gene variants have been found which are 'protective', i.e. individuals with these variants have lower risk of AMD, and which are 'causative', i.e. their presence results in increased risk. There are two main genetic regions that modify AMD risk. One, on chromosome 10, is poorly understood. The other, on chromosome 1, provides the code for a series of proteins called Complement Factor H (FH), Factor H-Like Protein 1 (FHL-1), and five proteins called Factor H-Related 1-5 (FHR1-5). These proteins are involved in regulating part of the immune system called the complement cascade. It is thought that genetic variations on chromosome 1 alter the amounts of these proteins, resulting in inflammation in the eye and ultimately to the development of AMD. This is supported by a number of studies where the absence of one of these proteins, or a change in its sequence (hence function) can be shown to change the risk of AMD occurring.While it is assumed that these AMD-associated genetic variants change the levels of FH, FHL1 and FHR1-5 present in the body, this has been difficult to confirm. These proteins are very similar (indeed FHL-1 is identical to the first half of FH, with the exception of a very small tag at one end). This means that standard methods, which recognise and measure a protein based on its shape are fraught with problems, as it is very difficult to prove exactly which form is being measured. In this project, we will take a different approach - mass spectrometry (MS). MS works by 'weighing' the molecules of interest, then counting how many of each are present. Since we know the structure of these proteins, we can calculate their mass and detect them with very high confidence. Indeed, MS is now routinely used for testing blood levels of many compounds as part of routine clinical care. We have developed an MS-based method which can measure the levels of all seven proteins of interest in plasma at the same time. This method will be of great value. We will use it to analyse blood samples where we have already used standard methods and see how the results match, showing which methods are reliable. Secondly, we will measure the levels of these seven proteins in plasma collected as part of a large genetic study of AMD. The donors of these blood samples have already had their genetic profile determined. By measuring the amounts of protein, we can compare with the genetic data and see for the first time how the genetics impacts on the levels of each protein, and in turn how the levels of these proteins confer AMD risk. This research will provide new understanding as to how AMD develops, will improve our ability to define risk, and may allow the development or monitoring of new treatments.This assay will also be useful for research into other diseases. These proteins are known to be important for certain kidney diseases and reliable ways to measure them will be important both for research and clinical care. There is also evidence that they contribute to other conditions such as Alzheimer's disease.