2-Pyrrolidinone and Succinimide as Clinical Screening Biomarkers for GABA-Transaminase Deficiency: Anti-seizure Medications Impact Accurate Diagnosis
2-Pyrrolidinone and Succinimide as Clinical Screening Biomarkers for GABA-Transaminase Deficiency: Anti-seizure Medications Impact Accurate Diagnosis
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DOI：
10.3389/fnins.2019.00394
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发表时间：
2019-05-08
影响因子：
4.3
通讯作者：
Elsea, Sarah H.
中科院分区：
文献类型：
--
作者：
Kennedy, Adam D.;Pappan, Kirk L.;Elsea, Sarah H.
大规模非靶向生化表型分析是一种补充广泛接受的检测的技术，例如通常用于诊断先天性代谢缺陷的有机酸、氨基酸和酰基肉碱分析。在本研究中，我们研究了与 4-氨基丁酸转氨酶（ABAT、GABA 转氨酶）缺乏相关的分析物变化以及影响 GABA 代谢的治疗方法。 GABA 转氨酶缺乏症是一种罕见的神经发育和神经代谢疾病，由 ABAT 突变引起，并导致 GABA 在脑脊液 (CSF) 中积聚。因此，脑脊液中 GABA 的测量是目前诊断的主要方法。 GABA 转氨酶缺乏症会导致严重的发育迟缓、智力障碍、癫痫发作和运动障碍，并且常常与儿童期死亡有关。使用非靶向代谢组学平台，我们分析了四名 GABA 转氨酶缺乏症患者的 EDTA 血浆、尿液和脑脊液样本，通过将个体患者样本的生化特征与以儿科为中心的人群队列进行比较来识别生物标志物。对 1,000 多个临床血浆样本的代谢组学分析揭示了丰富的生化信息来源。四分之三的患者血浆中 2-吡咯烷酮分子（Z 分数 >= 2）水平显着升高，全外显子组测序揭示了 ABAT 中意义不确定的变异。此外，这些患者的血浆、尿液和脑脊液中的琥珀酰亚胺和/或尿液和脑脊液中的高肌肽水平也升高。在对临床 EDTA 血浆样本的分析中，琥珀酰亚胺和 2-吡咯烷酮的水平显示出高度相关性 (R = 0.73)，表明 GABA 代谢受损，并进一步支持与 GABA 转氨酶缺乏和 ABAT 变体致病性的关联。对我们患者群体代谢组学数据的进一步分析揭示了 2-吡咯烷酮水平升高与服用氨己烯酸（一种常用的抗癫痫药物和已知的 GABA 转氨酶抑制剂）的相关性。这些数据表明，抗癫痫药物可能会改变生化和代谢组数据，可能影响对患者的解释和诊断。此外，这些数据证明了结合大规模基因分型和表型分型技术来诊断遗传性神经代谢紊乱的力量，并支持使用血浆代谢表型来筛查 GABA 转氨酶缺乏症。
Broad-scale untargeted biochemical phenotyping is a technology that supplements widely accepted assays, such as organic acid, amino acid, and acylcarnitine analyses typically utilized for the diagnosis of inborn errors of metabolism. In this study, we investigate the analyte changes associated with 4-aminobutyrate aminotransferase (ABAT, GABA transaminase) deficiency and treatments that affect GABA metabolism. GABA-transaminase deficiency is a rare neurodevelopmental and neurometabolic disorder caused by mutations in ABAT and resulting in accumulation of GABA in the cerebrospinal fluid (CSF). For that reason, measurement of GABA in CSF is currently the primary approach to diagnosis. GABA-transaminase deficiency results in severe developmental delay with intellectual disability, seizures, and movement disorder, and is often associated with death in childhood. Using an untargeted metabolomics platform, we analyzed EDTA plasma, urine, and CSF specimens from four individuals with GABA-transaminase deficiency to identify biomarkers by comparing the biochemical profile of individual patient samples to a pediatric-centric population cohort. Metabolomic analyses of over 1,000 clinical plasma samples revealed a rich source of biochemical information. Three out of four patients showed significantly elevated levels of the molecule 2-pyrrolidinone (Z-score >= 2) in plasma, and whole exome sequencing revealed variants of uncertain significance in ABAT. Additionally, these same patients also had elevated levels of succinimide in plasma, urine, and CSF and/or homocarnosine in urine and CSF. In the analysis of clinical EDTA plasma samples, the levels of succinimide and 2-pyrrolidinone showed a high level of correlation (R = 0.73), indicating impairment in GABA metabolism and further supporting the association with GABA-transaminase deficiency and the pathogenicity of the ABAT variants. Further analysis of metabolomic data across our patient population revealed the association of elevated levels of 2-pyrrolidinone with administration of vigabatrin, a commonly used anti-seizure medication and a known inhibitor of GABA-transaminase. These data indicate that anti-seizure medications may alter the biochemical and metabolomic data, potentially impacting the interpretation and diagnosis for the patient. Further, these data demonstrate the power of combining broad scale genotyping and phenotyping technologies to diagnose inherited neurometabolic disorders and support the use of metabolic phenotyping of plasma to screen for GABA-transaminase deficiency.