Metabolomic profiling of cerebrospinal fluid to improve diagnosis and treatment monitoring of patients with inborn or acquired errors of metabolism

本项目的目标是利用现代技术开发新的测试，以改善我们的诊断服务。我们的诊断实验室是一个NHS国家转诊中心，为怀疑有脑代谢异常的患者提供服务，特别是关于神经递质和维生素代谢（见下文）。我们用于诊断的样本类型是脑脊液（CSF）。我们每年收到大约1000份CSF样本。这些样本中有许多来自患有影响大脑代谢的疑似遗传性疾病的幼儿，导致他们出现运动障碍、发育迟缓或癫痫发作等临床症状。我们还接收老年患者的脑脊液样本，用于治疗监测或识别神经炎症、运动障碍（如帕金森病）或神经变性患者的潜在可治疗症状。脑脊液（通常缩写为CSF）是包围大脑和脊髓的液体。血液中的营养物质通过血脑屏障进入脑脊液。然后，CSF将这些营养物质带到脑细胞，并从大脑中清除废物，穿过血脑屏障，然后再循环或从体内排出。与血液相比，CSF颜色清澈，几乎没有细胞。这使得它成为观察大脑代谢的一个很好的干净矩阵。我们在体液中测量的小分子，如血液和CSF，被称为代谢物，帮助我们了解身体器官如何使用和回收饮食中的营养物质。研究代谢物还可以帮助我们识别和诊断身体不能有效利用或回收这些营养素的疾病。我们目前的CSF服务仅对约5%的患者进行明确诊断。然而，在我们目前的测试中，几乎有50%的人有未知意义的异常，如果可以测量更多的脑代谢物，这一比例可能会更高。这些患者可能患有未确诊的神经代谢疾病。该项目的目的是使用现代技术来增加我们可以测量的代谢物的数量，以便我们可以诊断这组目前未确诊的患者。我们目前有四种测试来测量CSF中的代谢物。这些测试是基于30年的技术，但非常可靠，我们有多年的经验来解释这些测试的结果。这些测试测量神经递质代谢物和维生素/辅因子，这些是神经递质合成和大脑中许多其他必需化学物质所需的。通过这四种测试，我们目前在CSF中总共测量了10种代谢物。我们将开发的新测试将使用质谱法，这是一种现代超灵敏和快速的技术。这项技术将使我们能够将我们可以测量的代谢物数量从目前的10种增加到30多种。虽然质谱仪能够测量更多的代谢物，但我们最初打算专注于较小的数量（约30）并根据需要进行扩展。这样我们就可以专注于假设在我们的患者组中受到影响的特定途径。这也将更容易确保该方法的稳健性、可重复性和准确性。目前，我们的诊断分析非常擅长突出大脑神经递质或维生素代谢的缺陷。然而，由于我们测量的代谢物数量有限，我们不能总是确定缺陷的确切原因和功能影响。现代质谱法将使我们更深入地了解大脑代谢，并使我们能够诊断和诊断目前未诊断的疾病。它还将使我们能够更好地建议和监测治疗。这将反过来改善受这些破坏性但通常可以治疗的影响大脑代谢的疾病影响的儿童和家庭的生活。

Summary The objective of this project is to develop new tests, using modern technology, to improve our diagnostic service. Our diagnostic laboratory is an NHS national referral centre for patients suspected of having abnormalities in brain metabolism, particularly with regards to neurotransmitter and vitamin metabolism (see below). The sample type that we use for diagnosis is cerebrospinal fluid (CSF). We receive around 1000 CSF samples per year. Many of these samples are from young children with suspected genetic disorders affecting brain metabolism, causing them to have clinical symptoms such as movement disorders, developmental delay or epileptic seizures. We also receive CSF samples from older patients for treatment monitoring or to identify potentially treatable symptoms in patients with neuroinflammation, movement disorders (such as Parkinson's disease) or neurodegeneration.Cerebrospinal fluid (often abbreviated as CSF) is the fluid that surrounds the brain and spinal cord. Nutrients from the blood are transported into the CSF via the blood-brain barrier. The CSF then takes these nutrients to brain cells and removes waste products from the brain to be transported back across the blood-brain barrier and either be recycled or excreted from the body. In contrast to blood, CSF is clear in colour and has little or no cells. This makes it a nice clean matrix for looking at brain metabolism. The small molecules that we measure in body fluids, such as blood and CSF, are known as metabolites and help us to understand how the organs of the body are using and recycling nutrients from the diet. Studying the metabolites can also help us to identify and diagnose disorders where the body is not using or recycling these nutrients effectively.Our current CSF service results in a definitive diagnosis in only around 5% of patients. However, almost 50% have abnormalities of unknown significance in our current tests and this is likely to be higher if more brain metabolites could be measured. These patients are likely to have an undiagnosed neurometabolic condition. The aim of this project is to use modern techniques to increase the number of metabolites that we can measure so that we can diagnose this group of currently undiagnosed patients. We currently have four tests that measure metabolites in CSF. These tests are based on 30 year old technology but are very reliable and we have many years of experience of interpreting the results from these tests. These tests measure neurotransmitter metabolites and vitamins/co-factors that are required for neurotransmitter synthesis and many other essential chemicals in the brain. With these four tests we currently measure 10 metabolites, in total, in CSF.The new tests that we will develop will use mass spectrometry, a modern ultra-sensitive and rapid technique. This technology will allow us to increase the number of metabolites that we can measure from 10 currently to over 30. Although mass spectrometers are capable of measuring many more metabolites, we initially intend to focus on a smaller number (around 30) and expand as required. This is so that we can focus on specific pathways that are hypothesised to be affected in our group of patients. This will also make it easier to ensure that the method is robust, reproducible and accurate.At the moment, our diagnostic assays are very good at highlighting defects in brain neurotransmitter or vitamin metabolism. However, due to the limited number of metabolites that we measure, we can not always define the exact cause and functional effect of the defect. A modern mass spectrometry method will give us much greater insight into brain metabolism and allow us to characterise and diagnose currently undiagnosed disorders. It will also allow us to suggest and monitor treatments better. This will in turn improve the lives of children and families affected by these devastating but often treatable diseases affecting brain metabolism.