Biochemical Genetics and Newborn Screening Laboratory, Department of Clinical Chemistry, Cliniques universitaires Saint-Luc, UCLouvain, B-1200 Brussels, Belgium; Groupe de Recherches Metaboliques, de Duve Institute, UCLouvain, Brussels, Belgium; Louvain Centre for Toxicology and Applied Pharmacology, Institut de Recherche Expérimentale et Clinique, UCLouvain, Brussels, Belgium.
Groupe de Recherches Metaboliques, de Duve Institute, UCLouvain, Brussels, Belgium.
Mol Genet Metab. 2023 Nov;140(3):107712. doi: 10.1016/j.ymgme.2023.107712. Epub 2023 Oct 24.
Glycogen storage disease type Ib (GSD1b) and G6PC3-deficiency are rare autosomal recessive diseases caused by inactivating mutations in SLC37A4 (coding for G6PT) and G6PC3, respectively. Both diseases are characterized by neutropenia and neutrophil dysfunction due to the intracellular accumulation of 1,5-anhydroglucitol-6-phosphate (1,5-AG6P), a potent inhibitor of hexokinases. We recently showed that the use of SGLT2 inhibitor therapy to reduce tubular reabsorption of its precursor, 1,5-anhydroglucitol (1,5-AG), a glucose analog present in blood, successfully restored the neutropenia and neutrophil function in G6PC3-deficient and GSD1b patients. The intra-individual variability of response to the treatment and the need to adjust the dose during treatment, especially in pediatric populations, can only be efficiently optimized if the concentration of 1,5-AG in blood is monitored during treatment, together with the patients' clinical signs and symptoms. Monitoring the 1,5-AG levels would be greatly simplified if it could be performed on dry blood spots (DBS) which are easy to collect, store and transport. The challenge is to know if a suitable method can be developed to perform accurate and reproducible assays for 1,5-AG using DBS. Here, we describe and validate an assay that quantifies 1,5-AG in DBS using isotopic dilution quantitation by LC-MS/MS that should greatly facilitate patients' follow-up. 1,5-AG levels measured in plasma and DBS give comparable values. This assay was used to monitor the levels of 1,5-AG in DBS from 3 G6PC3-deficient and 6 GSD1b patients during treatment with SGLT2 inhibitors. We recommend this approach to verify the adequate therapeutical response and compliance to the treatment in G6PC3-deficient and GSD1b patients treated with SGLT2 inhibitors.
糖原贮积病 1b 型（GSD1b）和 G6PC3 缺乏症是由 SLC37A4（编码 G6PT）和 G6PC3 的失活突变分别引起的罕见常染色体隐性疾病。这两种疾病的特征均为中性粒细胞减少症和中性粒细胞功能障碍，其原因是 1,5-脱水葡萄糖醇-6-磷酸（1,5-AG6P）的细胞内积累，这是一种葡萄糖类似物，是己糖激酶的有效抑制剂。我们最近表明，使用 SGLT2 抑制剂治疗来减少其前体 1,5-脱水葡萄糖醇（1,5-AG）的管状重吸收，该物质是血液中存在的葡萄糖类似物，成功地恢复了 G6PC3 缺乏症和 GSD1b 患者的中性粒细胞减少症和中性粒细胞功能。如果在治疗期间监测血液中的 1,5-AG 浓度，以及患者的临床症状和体征，则可以高效地优化个体对治疗的反应的个体内可变性和治疗期间的剂量调整。如果能够在干血斑（DBS）上进行监测，那么监测 1,5-AG 水平将变得更加简单，因为 DBS 易于采集、存储和运输。挑战在于要知道是否可以开发出一种合适的方法，以便使用 DBS 对 1,5-AG 进行准确和可重现的测定。在这里，我们描述并验证了一种使用 LC-MS/MS 通过同位素稀释定量法在 DBS 中定量 1,5-AG 的测定方法，该方法应极大地便于患者的随访。在 DBS 和血浆中测量的 1,5-AG 水平给出了可比的值。该测定法用于监测 3 名 G6PC3 缺乏症和 6 名 GSD1b 患者在接受 SGLT2 抑制剂治疗期间 DBS 中 1,5-AG 的水平。我们建议采用这种方法来验证 G6PC3 缺乏症和 GSD1b 患者接受 SGLT2 抑制剂治疗的充分治疗反应和治疗依从性。
