Newborn screening and treatment monitoring for patients with pyridoxine-dependent epilepsy

项目摘要： 吡哆醇依赖性癫痫（PDE）是一种发育性和癫痫性脑病， 其定义为对吡哆醇的阳性临床反应。尽管有充分的控制，但大多数 患者有发育迟缓和智力残疾。PDE是由于α-氨基己二酸缺乏所致 半醛（α-AASA）脱氢酶，赖氨酸代谢中的一种关键酶， α-AASA和相关代谢物的蓄积。我们最初专注于减少α- AASA通过赖氨酸限制饮食和赖氨酸转运的竞争性抑制剂。这些新疗法 策略改善了整体生物化学，并与正常的认知发展有关。 虽然有效，但治疗必须在生命早期开始，以防止不可逆转的脑部疾病。 不幸的是，大多数患者是在治疗无效后才确诊的。我们的核心假设是 诊断和后续治疗的延误是智力残疾的主要原因， 与这种疾病有关。 本申请的主要重点是为PDE患者开发新生儿筛查方法。 新生儿筛查提供了在不可逆神经损伤之前诊断患者的机会 会极大地改变这种疾病的自然病程。以往的新生儿筛查尝试 由于α-AASA在室温下不稳定，因此对新生儿不实用， 筛选在我们之前的工作中，我们鉴定了一种新的生物标志物（6-氧代-哌可酸），其在室温下稳定。 并克服了以前新生儿筛查的障碍。我们将证明新生儿 使用目前的新生儿筛查技术，可以在出生时诊断出PDE（目标1）。这些结果将 确定受影响新生儿的6-氧代哌啶酮升高，并为未来的研究提供基础 关注我们新生儿筛查方法的灵敏度 虽然α-AASA是一种很好的诊断生物标志物，但α-AASA的水平与疾病无关 严重程度或认知结果。这些结果被α-AASA的不稳定性质所混淆， 这使得很难比较样本和实验室之间的水平。我们的目的是，6-氧-哌可酯是 是监测治疗效果的理想生物标志物。我们将评估在家收集方法的使用 使用我们现有的干血斑法测定6-氧代-哌可酯。在家治疗的好处 由于新型冠状病毒，监测从未像当前这场大流行期间那样重要 新冠肺炎。我们将证明，从家中收集的干血斑中测量6-氧代哌啶酸盐 是可行的（目标2）。这些结果将是关键的未来研究评估新的治疗 治疗这种可治疗但严重的神经系统疾病。

Project Summary: Pyridoxine-dependent epilepsy (PDE) is a developmental and epileptic encephalopathy that was historically defined by a positive clinical response to pyridoxine. Despite adequate seizure control, the majority of patients have developmental delay and intellectual disability. PDE is due to a deficiency of α-aminoadipic semialdehyde (α-AASA) dehydrogenase, a key enzyme in lysine metabolism that results in the accumulation of α-AASA and related metabolites. We initially focused on reducing the accumulation of α- AASA through a lysine-restricted diet and a competitive inhibitor of lysine transport. These novel treatment strategies improved the overall biochemistry and are associated with normal cognitive development. Although effective, treatment must be started early in life to prevent irreversible brain disease. Unfortunately, most patients are diagnosed after treatment is no longer effective. Our central hypothesis is that the delay in diagnosis and subsequent treatment is the main contributor of intellectual disability associated with this disease. The primary focus of this application is development of a newborn screen method for patients with PDE. Newborn screening provides an opportunity to diagnosis patients before irreversible neurologic damage occurs dramatically changing the natural history of this disease. Previous attempts at newborn screening were unsuccessful as α-AASA is unstable at room temperatures and, therefore, not practical for newborn screening. In our previous work, we identified a novel biomarker (6-oxo-pipecolate) that is stable at room temperatures and overcomes previous hurdles with newborn screening. We will demonstrate that newborns with PDE can be diagnosed at birth using current newborn screening techniques (Aim 1). These results will establish that 6-oxo-pipecoalte is elevated in affected newborns and will provide the basis for future studies focused on the sensitivity of our newborn screening method. Although α-AASA is an excellent diagnostic biomarker, the level of α-AASA does not correlate with disease severity or cognitive outcome. These results are confounded by the unstable nature of α-AASA, which makes it difficult to compare levels between samples and laboratories. We purpose that 6-oxo-pipecolate is an ideal biomarker to monitor treatment efficacy. We will evaluate the use of an at-home collection method for 6-oxo-pipecolate using our existing dried blood spot method. The benefit of at home treatment monitoring has never been more relevant than during this current pandemic due to the novel coronavirus COVID-19. We will demonstrate that measuring 6-oxo-pipecolate from dried blood spots collected at home is a feasible (Aim 2). These results will be critical for futures studies evaluating novel therapeutic approaches to this this treatable but severe neurologic disease.